@Dragoon: Yes, you're trolling. The powerslide has more depht in MKWii, you can still get it work in the same fashion as before. And the 2 phase boost with karts is a nice addition.
The reviewers complain about the lack of snaking in the straights (which was shit anyways). In general the game has a lot more depht than the previous ones, i have owned the game since day after launch, and still get surprised realising new things about the game. One thing that had a big change is, that you can't you can't build up your racing strategy on using items tactically (the 12 player races contribute a lot to this), the tracks are extremely well balanced and how you should drive them, depends on what vehicle you chose (there's a lot of difference between different vehicles).
Actually even the "luck factor" have been reduced greatly, since getting certain items depends on your position even more than before. Besides, if you drive fast enough and get to run away from others, they can't catch you. 2-3 blue shells (which are the only ones that can hurt you, when having a decent lead) per race (depending on track) doesn't prevent you from winning, unless someone is skilled enough to catch you.
Edit: And yes, Rol is more credible. You are reading reviews that are based on few hours of gameplay, before you learn how the game works, and when you read our posts, you're reading opinions of people, who each have as much gaming experience from the game, as all the reviews combined.