I didn't think that Mario Kart 7 was a BAD game, but there are nonetheless a few things that bother me:
-The AI can be pretty unbalanced, especially in the 150cc and Mirror Modes; AI drivers can have the most miraculous aim/timing for various things (e.g. I can remember a few times where I've had the Super 7 item cycling around me with the Star, only for a CPU driver to be able to ZERO IN ON MY STAR AND SWIPE IT FROM ME LIKE THE THIEVING FUCKER IT IS).
-No Boos or Fake Item Boxes (although, considering Nintendo's decided to make the Fake Item Boxes completely damned obvious in later Mario Kart outings, the loss is a mixed bag).
-Most of the courses just aren't exciting, especially the Battle Courses; also, the addition of glider and water sections feel forced, and many of those in the Retro Circuit just absolutely destroy the challenge originally present in those courses (N64 Koopa Beach, anyone?).
-The return of coins from SMK/Super Circuit is cool at first, but you can only hold ten per course (which especially blows considering how many surplus coins you can often pick up in a race after reaching 10), and to unlock additional Parts, you need to collect these coins, which segues nicely into my next issue...
-The scaling of intervals of coins you need to collect for later parts is ludicrous, with the last five requiring collecting 500 coin intervals. Oh, and almost all the parts unlocked are random, which is obnoxious.
-Some character choices are ridiculous, and this is where I lose any remaining patience. Right off the bat, Wario is hidden, in favor of Koopa Troopa. You unlock Mii fairly quickly, but all the others must be unlocked in the 150cc, and considering most players are gonna go for the lower classes first, that leaves the majority of players without additional characters for a decent length of the game. Also, some of the hidden characters straight up suck; namely Queen/Honey Bee, Lakitu, and Wiggler. Queen Bee had a very small role in Super Mario Galaxy 2, so I dunno why they'd think she would be great; Lakitu's already the referee, and Wiggler appears as a massive-sized obstacle in Maple Treeway. However, these aren't even the worst choices...
-METAL MARIO. METAL FUCKING MARIO. Yes, I do think this asshole deserves his own listing. The other characters I bitched about were at least unique, differing designs; Metal Mario is literally a weight and texture swap of Mario. All these lousy characters waste precious character slots, especially when characters like Waluigi, Diddy Kong, Dry Bones, Birdo, or what have you are more deserving.
tl;dr version:
-the AI needs some further balancing
-items leave a bit to be desired
-most course designs are OK at best, but not terrible (however, I do like the ones that are a single stretch instead of a lapping loop, like Maka Wuhu)
-the gliding and underwater segments feel too gimmicky and can break some old courses
-limits on coin collecting can be bothersome, especially when later Kart Parts require tons of coins
-absolutely silly roster choices
However, there are things that DID please me about the game:
+the Kart customization; it's fun to see what works best for you
+all courses are available for online play (fuck yourself, Mario Kart DS)
+the gameplay is very solid
Conclusion? As I said, it's not godawful (at least not so much as MKWii), and I actually think it's at least worth checking out a demo (if there is one). At the very least, you'll probably get more fun out of this than, oh say, Paper Mario Sticker Star (that rant is for another time, though).