Found this on mario kart wii board.
It's still too early for me to say for sure which game is more fun. Despite the amount of text, I still have fun playing MK8 for what it is. A lot of us have had years of playing and adapting to MKWii. Personally, I've been playing the game feverishly since 2008 and I still enjoy it for all the reasons that I initially fell hooked. But, I will tell you about the largest factor that leaves a large dent in my overall enjoyment with MK8:
The controls, projectile item speed, and tricks (in that order of importance).
At least in MKWii, you can dodge items. Vehicles had fast response times to changes in drift. They didn't fly all over the map with excess outward momentum. They didn't violently ricochet all over the map over a mistake. And, even without stand still mini-turbos, you were still able to recover from hits without sliding outwards and wiggling around. When you started a drift, you locked into that direction and you were not subjected to drifting the wrong way nearly as much as in MK8. You were able to trick and hold a drift. The controls were sharp and precise, allowing you enough time to dodge green shells, which charged at you somewhat slow compared to MK8.
In MK8, projectile items were sped up and vehicle controls were made to be more sluggish, so you cannot dodge anything shot at you. Ever. Nintendo has placed far too much energy on making items benefit the user. They have made all projectile items, including reds and blues, more powerful than the previous game. Projectiles are too fast. They've given those who possess those items god control over who lives and who dies. If you have a green, a fire flower, a boomerang, etc., there is almost no chance your victim will be able to escape it because the victim is racing on a wind-up toy car that doesn't move fast enough to avoid the projectile. The vehicle controls make players sitting ducks.
I would have been happy if they would have given the player a range of options when controlling their racer to at least give them a chance to evade a green shell or machine gun fireballs. I also would have settled for slower projectile speeds, but if I had to choose one, I would much rather have more control over the vehicle. I don't like driving a plate spaghetti.
In MK8, tricks are too fast, too stumpy, and lack a lot of personality. They're not as flashy and you cannot perform them while drifting. Why they thought setting the drift and trick functions to one button is beyond me, especially considering the fact that the gamepad has 4 shoulder buttons. Nintendo, separating and isolating functions to specific and independent buttons tends to offer a wider variety in control options and makes the difference between more skilled and less skilled. People like to compete in this area. Players like to feel like they're in control and not throwing spahgetti all over the place.