Ring Racers is a gem, the somewhat lengthy tutorial and the mostly fixed single player rubber-banding won't take that away from it.
This game joins CTR in the field of kart racers that just "get it", it's very technical with a lot of inter-woven mechanics making the game a blast to play and get better at. The ring-feeding being a variant of the F-zero boost mechanic adds a lot of strategy and intense moments compared to robo kart, I love that the devs went and honed such disruptive ideas, really ends up being a breath of fresh air in the kart racing field.
On the presentation side I think the game has a pretty strong themeing which really transpires in both visuals and soundtrack, there is a staggering amount of content (like 8 times the amount of tracks in a typical new mario kart) though the circuits still managed to be highly varied but still consistent with the core theme, of course the sonic (& some sega) IP helps with its long history but the fan-service is a given in such a project and if anything makes it easier to love.
I also want to mention the single player progression which I think is really well realized, it uses a similar system to the challenge wall in smash brawl, which lets you play the game as intended but keeping side objectives in mind, it really encourages you to play more of the game and feels good feeding you rewards regularly, also have the option to skip some of the challenges if you feel like it. I also like how many secrets are hidden among the tracks, it's really fun to explore familiar areas in a new light and discover all the effort that went into them (most of them being linked to unlocks too).
Overall this is an amazing fan-project that isn't afraid to push its genre forward, both in mechanics and how it handles progression, and a beautiful love-letter to the sonic IP.

Originally, I posted a review comparing this game to other titles with a ton of depth that demand a lot from the player (like IIDX, +R, etc). I deleted that review, because I wasn't totally sure where I stood on the game after a few more races.

And then after doing even more races, I realized I was right the first time. This game fucking rules.

The tutorial is still awful, but I'm really glad I did it because I would not have thought to use stuff like quick drop without it, and the dialogue between Tails and Robotnik is endearing. It's probably the worst part of the game, and it's irrelevant after the first 45 min outside of the on-boarding process for new players. "Oh, you think you're hot shit? Beat this max CPU level race then" is based, actually.

Otherwise, it's a kart racer that asks more from you than most other entries in the genre, and that's rad. The ring system is sick as hell. The courses aren't all bangers, but an overwhelming majority of them are, and they all look and sound so good that you genuinely forget that the game is a fan project.

The Brawlesque unlock system is only frustrating if you want all the content at once and don't give a shit about the single player experience. The actual process of unlocking everything is, much like it was in Brawl, a fantastic way to encourage new players to plumb the depths of the game, and the key system lets you skip over any challenge you find especially egregious.

Nobody's mentioned the little pets that you can have follow you. I love having a little guy around me at all times for emotional support. No notes, should be a feature in more games in general.

This game is not trying to replace SRB2Kart, and divorced from the context of that game, I don't think it would have nearly as bad of a reputation. The average rating on this page has gone up steadily since this game's release, and as I posted before, in six months after the rough patches of the game are smoothed out (as they have been already in some cases!), it'll be appreciated for the home run that it is.

HOW IS THIS THE MOST POLARIZING GAME ON ALL OF BACKLOGGD AHAHAHAHAHA LOOK AT THAT RATING DISTRIBUTION

It's a maximalist kart racer which throws anything and everything in because the developers are as talented and prolific as they are sadomasochistic. Or more charitably, they knew people typically played SRB2K with heavily modded servers, and sought to kill two birds with one stone by making their sequel filled with an intimidating amount of content. While plenty of new mechanics are introduced, the game's namesake helps balance out the grid in a highly volatile but ultimately successful way. Chugging rings and speed-gating shortcuts might seem as baffling as... Well, everything else in DRRR (what an acronym) but it's sensible in the same madcap way every other goddamn thing here is. Hell, even the positioning system before a race starts helps even the field more than first impression would suggest.

At first I was perturbed by everything being locked behind a Brawl / Kirby Air Ride style checklist (or most, as of v2.1) but it's so endearing. Consider it a hot take but what a blessing in disguise that Kart Krew felt committed to making you commit to playing their game to an unhealthy degree. That kind of cocky energy is so rare these days, especially given that the passwords are included in the game folder to tempt the player constantly. "Oh, what's wrong, too many spray cans for you, hmmm?"

If you're still on the fence, play for at least another hour, because it will click. I don't see this replacing SRB2K whatsoever but it's an utter monolith of a game. I HATE BALLOON PARK I HATE BALLOON PARK I HATE BALLOON PARK I HATE BALLOON PARK I HATE BALLOON PARK I HATE BALLOON PARK I HATE BALLOON PARK