The mere fact that this game has been around for 10 years should be enough of a reason to rate it two stars.
Jokes aside, there's something about Mario Kart 8 Deluxe that just doesn't sit right with me.

It's as if they've polished the game to the point that the series' trademark liveliness vanished, thus leaving a bland kart racer that lacks both the personality and thrilling driving of the previous games. Long gone are the days when you could pull off cool stunts, discover unintented shortcuts, or simply explore the tracks on a whim, the boundaries here are much more controlled and if you try something wacky, that bozo of a Lakitu will show up and ruin the fun.

Let's talk about the tracks. Their visuals are nothing short of amazing. I was often left in awe of the sheer beauty and level of detail Nintendo managed to achieve, so kudos for that. If I look past the pretty graphics, though, there are a few things that irk me about the tracks, namely the anti-gravity sections. I feel they could've handled the anti-gravity gimmick a lot better since it fails to impact the gameplay in a relevant way and barely adds anything. I also wanna add that the booster pass tracks are nothing to write home about, with only a handful of them being on the same level as the ones from the base game.

What ultimately drags Mario Kart 8 Deluxe down though is an excruciatingly broken item system, which may be the worst in the entire series. Someone at Nintendo HQ really thought it would be a good idea to balance items around the distance rather than the absolute position, with the catastrophic consequence of players randomly getting overpowered items in middle positions when the frontrunner gets a breakaway. This convoluted chaos degenerates even further thanks to the double-item boxes that basically encourage players to spam relentlessly everything they land their hands on.
Single-player mode was another huge letdown for me. I think it's about time they step up and create a full-fledged story mode like the ones in Crash Team Racing and Diddy Kong Racing, playing the cups over and over just doesn't cut it anymore. In this game it feels even more pointless since all characters are unlocked from the get-go anyway.

In light of all of this, Mario Kart 8 Deluxe never felt like the definitive Mario Kart experience to me.
Nintendo pulled the wool over fans' eyes with a staggering number of tracks and delivered the biggest Mario Kart to date, but despite all of this, the charm is just not there.

Mario Kart 8 Deluxe takes what the original game on the Wii U offered and added more through the available options, updates, and the addition of the Booster Course Pass.
The available characters, new karts, bikes, and ATVs give players the ability to customize as freely as they are able. Each track is not only creative and lively in their own way, but are also suited for the different classes of racing.
With the new battle arenas dedicated to Battle Mode, it makes each mode easier to navigate and race on in solo play or on teams.
Compared to other Switch games, Mario Kart 8 Deluxe has seamless online connection for racing regionally and globally, and it is very fun to play online with other players.
With the new updates such as a Jukebox mode and an additional 48 tracks added through the Booster Course Pass, there is much more offered on top of a fantastic game.
Until we get an announcement for Mario Kart 9, the new updates add so much to an existing game that is both welcoming to newcomers and veterans of the series.

My thoughts on this are largely the same as on the vanilla version, which you can read here.

Deluxe adds, changes, and removes a few things, and overall it's the very slightly better version. The Smash Bros.-style custom item options for vs. races is something I'd been wanting in the series for many years.

New characters and vehicle parts have been added, and there are more distinct stat classes for all of them which is an appreciated touch.

Battle Mode has proper arenas now, but most of them seem a tad too large for 12-player matches. Balloon Battle is still missing a traditional elimination-style, no-timer option in offline play, but the addition of the excellent Renegade Roundup mode makes up for that for me anyway.

Fire-hopping has been removed, but it was such a lame and inconsequential technique compared to the crazy stuff you can pull off in Double Dash or Wii, so 8DX doesn't really suffer much from it's removal.

Standard Online matches now cycle between 150cc, 150cc Mirror, and 200cc, which is more irritating than anything, but I suppose it's not a big deal.

I didn't touch on it in my Mario Kart 8 review, but Time Trials still has coins and I wish they removed that. Time Trials should be about finding the fastest lines through a track, not routing for coins.

The DLC is underwhelming and lazy, but I'll write my complete thoughts later in a dedicated DLC review.

I have a weird relationship with this game. I bought the first when it came out on Wii U nearly 10 YEARS AGO, and since then I will say that yea, it has gotten kind of repetitive. However, the fact that a game like this has this much longevity is ASTOUNDING, and should not negatively impact how perfect of a Mario Kart game this is. I will say that I'm still unimpressed with the battle mode after revisions. I wish Nintendo allowed for more customizability with the battle mode, setting time limits, having tournaments, setting items, almost in the same way Smash Bros does it.