I played this 90% of the way through, only missing the Varia Suit and 7 Chozo Artifacts, but I shelved because I feel like I've seen most of the game and can form an opinion it.

I always find it hard to review Metroidvanias, as I often find myself pondering the question : am I lost because I'm dumb, or am I lost because the game hasn't done a good job at helping me ? I feel like your enjoyment of a metroidvania will wildly vary depending on how often you got stuck, but I do feel like a good metroidvania makes sure that you never get stuck too long, by indicating to you if you've done everything you could in a room for example, or by having a small number of "keys" that will work on a large number of "locks". I feel like Metroid Prime doesn't do the best job at telling you where to go, and has too many upgrades, which makes them not feel as useful as they should.
The game is good, great even if you are a hardcore Metroidvania fan. I enjoy them, but I do have to say that I prefer the ones that subtly guide you, which Metroid Prime did not do. It is the exact opposite to Metroid Dread: the latter is really linear, and sometimes even quite restrictive, whilst Prime can be incredibly opaque.
Simply put, the map feels small, and it feels like you are always going through the same rooms over and over again. Furthermore, it feels like the game does the worst job at subtly telling you where to go next, so I ended up wandering about very often, looking for a spot to use my new upgrade. Also, you'll see very early on a lot of areas that are restricted by upgrades, so even if you do memorise all the spots that are restricted by an upgrade, you then have to go to each and every one of them to check which of the half-dozen you saw is actually important. You'll get "incoming scans" every now and again to point you to an important area, but there were two that never actually popped up on my screen, and I only know they exist because walkthroughs told me "you should get this message on your screen." Also, f*ck X-ray visor-based progression, it just feels horrible as you kinda need to get lucky to think about using it and there's never any real environmental clue to tell you to use it.

However, when the game works, it works. I wouldn't recommend playing with a guide (except if you're starting to get frustrated) because that feeling of everything clicking together is very satisfying. The game is at its best when you are making major breakthrough after major breakthrough, quickly breaking the puzzle. But then you'll miss the one important thing and you'll be stuck again, only to realize you missed somehting trivial, like a breakable wall that you didn't see.

A few sidenotes:
- Not enough savepoints
- Hard to find a consistant strategy to avoiding damage in projectile-based combat
- I hate fast-travel usually, but I feel like this game would benefit from it

Metroid Prime is a classic, that's easy to understand why. I do however feel like the game works best when you have played it at least once, and that you have a rough idea of where every upgrade is and a vague plan in mind. Please play it, especially if losing yourself in a metroidvania is your schtick. If you enjoy metroidvanias but kinda hate getting lost, abstain or at least be prepared to read a walkthrough every now and again.