Go play Dark Souls III or Sekiro instead. There are 2 good bosses in the game: Malenia and Rennala. The rest are an absolute mess of game design, easy, or just plain annoying. Soul of Cinder, despite not even being the best boss in Dark Souls III, is an absolute masterpiece of game design in comparison to whatever the fuck the final boss of Elden Ring is.

It's a shame because the overworld is quite fun to explore and the souls formula adapts pretty well to an open world format, but holy fuck is the rest of the game bad. Reused bosses (I've killed Godskin Apostle 5 times), artificial difficulty spikes by boosting health or damage of mobs/bosses, poor balance, lack of planning around certain builds, bosses become trivial with certain builds.

Elden Ring's boss design fails on both the perspective of a new player, and the perspective of a returning veteran. Everything I say is going to be in direct comparison to Dark Souls III which has a great difficulty curve and very enjoyable and memorable bosses.

As a new player, you require the game to teach you how to play itself. This isn't true for everyone, some people enjoy die and retry games, which admittedly souls games are, but there are a few a effective ways of playing Souls games that players would learn if they started with Dark Souls III. When starting Dark Souls III, you are greeted with three encounters. Iundex Gundyr, who isn't that amazing, but his purpose is something akin to showing the player how they will die and bosses will be challenging. As a new player to beat this boss you have to learn how to roll from attacks, or how to block and punish. Block/dodge and punish is the main way of dealing damage to bosses. The second encounter, Vordt, is the first colossal boss you'd face and what you will learn from Vordt is aggressively rolling behind a boss. I remember dying to Vordt a few times before friends told me to stick to his ass. The third encounter, a choice between Crystal Sages and Deacons of the Deep (both suck tbh) or the Abyss Watchers, is where a new player would seriously learn to watch for patterns, learn when to punish, and learn how to position themselves in regards to the boss, which is what is required to beat the Abyss Watchers.
In Elden Ring, you're greeted with Tree Sentinel who is hard to kill if you've never played a souls game, and lowsy dungeon bosses which effectively teach you nothing and aren't memorable. There wasn't a single boss in Elden Ring that I remember having deliberate pattern designs for the player to overcome in a specific way, other than Malenia. This is the price of freedom of gameplay, and this always leads to cheese. I could have easily beaten most of the major bosses by summoning a mimic or Luthel, popping my infinite mana physik, and doing Comet Azur. There are a few bosses designed with cheese in mind, like Rennala being a challenge (as a magic user) even if you summon something or Malenia dodging 90% of what you throw at her, but I am certain that Elden Ring doesn't teach you how to play souls games properly. There is always something you can do to make an encounter easier, you can easily respec, summons are op, spells are op, most builds are op, you can stagger most bosses with few strikes with str and dex builds, e.t.c. I'm sure new players can still enjoy the game, but they would have a hard time when trying out others in the line up.

As a returning player, what you're looking for in souls game is a fair challenge. You've had an excellent example of ramping and balanced difficulty in Dark Souls III, you've been through challenging and rewarding bosses, and Elden Ring falls flat on its face when it comes to providing a fair challenge, either with unfair bosses, either with not challenging bosses. I had to actively limit myself by not cheesing bosses with my magic beam and by not summoning to make the game challenging, and even then, most bosses were easy until you get to Maliketh or so. I will admit, up to Caelid, I was enjoying the game. After Radahn, I was hit with the classic more health more damage and would get two shot with 40 vitality, as well as bosses that are just roll to the side and wait, roll to the side and wait, rince repeat. Malenia is an excellent boss exactly for this reason, her attacks are hard to dodge, you have to react to them most of the time, Waterflow Dance will hit you, and to add insult to injury, she heals when she hits you, so you try your best to get every single hit in, and guess what, you get rewarded for it because you can stagger her. Malenia rewards well timed braveness, and god damn is it satisfying to dodge Waterflow Dance. After beating her you feel like you've climbed over a massive hurdle, like you could go back to earlier bosses and kick their ass because you've effectively gotten better at the game. This isn't to say that Malenia can't be cheap or can't be cheesed, she outright dies to str and dex builds because of stagger, but she's an excellent example of how bosses should be made. You should be rewarded for learning patterns, reacting, and punishing when necessary, you shouldn't be fucked over by RNG when punishing because the boss decided to prolongue his attack or delayed an attack AHEM RADAGON AHEM, a boss shouldn't just throw shit at you for long periods of time, a boss should challenge you as a player and require you to use everything you've learned up so far to beat them. This is what Elden Ring lacked.

It's as if nobody from Fromsoft playtested the damn game.

Dark Souls 2: The Sequel

Too many bosses of questionable quality with reuse, a defensive stat with poorly communicated benefits that is virtually required (Vigor and damage scaling vs Adaptability), heavier emphasis on RPG elements and builds (with easy respeccing), fights that encourage hit trading unless using specific builds, stark contrast between boss and area difficulty (i.e. Elden Ring bosses are much harder, DS2 areas). I could go on but you get the idea.

Elden Ring shines in it's opening hours, the world is refreshing (at first) extremely visually striking, and the discovering of new locations, dungeons, and loot feel more substantial and feeds an enjoyable exploration experience. However this luster starts to wane the longer you play. The "chalice dungeons but somehow worse" start to become routine after a while, especially considering you only get 1 item of value from them, which given the build emphasis of this game 95% of these items will be useless to you. And it would seem that after those initial hours of exploration most people eventually end up turning to the internet to simply look up where the items of value are rather than continue engaging in trivial, boring, reused areas and enemies. Heck, the fact that the most popular ending by far is one tied to a very long hidden quest chain shows pretty clearly most people play the game this way, which goes strongly against the exploration the first few hours of the game bring, and is being praised for.

Speaking of said open world, it sucks. Okay, okay. It looks incredibly striking, but in terms of actual content... ehhhhh. The souls style combat doesn't lend itself well to super open areas like this, and the horse combat being universally considered bad doesn't help with that. So all you have in that regard is the exploration, freedom, and sense of discovery. Which, I believe, for almost everyone dies out after a while when the rewards system of the game, and the over-reliance on reused enemies and areas start to click with people.

That all being said I do think Elden Ring has examples of really good exploration, some of the best in any game... in the legacy dungeons. Leyndall and Stormveil are two of the finest areas in any fromsoft game, with an absurd amount of secrets and paths through to find and explore, same goes for a lot of the underground. The only singular moment the entire overworld has even close to this is that first ride down the Siofra Elevator. And considering most of the game is said overworld, which pretty quickly starts to blend into a standard AAA open world only without annoying map and compass markers, and with a much more artistic and visually striking landscape.

The other biggest issue I have with Elden Ring pertains to the gameplay. Primarily in regards to game balance, and the bosses. Everyone knows the game has balance issues between the endgame and certain builds/weapons being too much superior to the others. But those problems are exacerbated by the new boss design. Very aggressive, poor numbers balancing, overuse of delay and aoe attacks, all multi-foe bosses being non-designed, input reading combined with input buffering, unavoidable damage. None of these individually are new to the series by any means, plenty of bosses are super aggressive, mainly in Bloodborne and some in DS3, same for delay attacks, some input reads, and input buffering has always existed. But combine it all with poor number balancing, and poor weapon/arts balancing, and make these all true of the majority of main bosses. Take Radagon, who isn't close to being one of the worst bosses in the game by any means. His teleport is borderline unavoidable damage, the delay on his grab is comically long it looks silly, plenty of his attacks have added aoe or delayed aoe, he blocks many build types (i.e. holy, status effects, overly slow colossal weapons etc.) And he is probably the best of the end-game bosses.

Elden Ring does add some flavor to what is essentially DS3, but it's pretty mixed imo. Mainly jumping. Defensively it is pretty bad, with little indication or consistency on what moves can or can't be avoided with jumps. Whereas offensively, jump attacks are the only thing keeping colossal weapons usable for super aggressive bosses. Jump attacks also encourage something the series has largely been moving towards dis-encouraging, which is disengaging. Combine enemies with combos that last too long, no tanginable benefit for most defensive actions besides damage mitigation, with spells, weapon arts, and jump attacking, and your best option for many bosses is to just... leave when they do their super long combos, and come in for a big hit with a jump attack or art which also contributes more to posture breaking. Sure you can criticize DS3 for R1 spam, but I'll take that over the way Elden Ring encourages unfun playstyles to tackle many of it's bosses.

Arbitrary favourite bosses: Godrick, Loretta, Rykard... just them.

Least Favourite: All the multi-foe bosses (special shout out to Godskin Duo, and the three rotten Crystallan's in a random mine), Melania, Maliketh, Fire Giant, all the dragons after the first one, probably a lot more.

One last random point in this rambling about why this game is mid, is that the souls series already had better self-driven exploration and feeling of discovery than virtually all other games, and the open world is actively detracting from that by merely stretching the game out, diminishing impactful moments and encounters by repeating them, and delegating random items important for certain builds or playstyles to garbage tier mini-dungeons with no indication of what you will get, turning that initial impressive exploration into a chore pretty quick as the player picks up on all of these factors.

Unironically DS2 is better as a gameplay experience since it embraces it's RPG elements more and waste's less time.