So first off, I'm going to say this will cause a decrease in grades in my upcoming semester(s). But I digress..
It looks like a great game. From what I can see the MTs look like a modified version of what MK-Wii does. It looks to have a little bit more sliding-style of MKDS, but the MTs still look like MK-Wii.
I like the whole 'more customization' thing. This could offer a new set of options that aren't just character and kart. If I'm guessing correctly, the wheel size will probably be similar to F-Zero's "Accel --> Max Speed" slider. For example, bigger wheels would be higher speed, but slower acceleration; small wheels = fast acceleration, but not a huge top speed. But thats only a guess - but it makes sense to me.
Anyways though, I'm glad to see some of the longer tracks back. I just hope they still put in a good deal of short tracks though; I wasn't a fan of how MK-Wii generally went towards longer tracks. Also, the whole water and air thing will be very cool. I can't wait to see what will come of it. I feel like someone is going to do something stupid though and make plenty of SCs with the glider. haha. Hopefully there wont be a boatload of shortcuts similar to MK64's Rainbow Road.
*Note to all friends (if this game is good): I will be playing this game, I will be coming back to MK, Pulsar will still drink, Moonside/Jeff/Arcadia/Whatever will still lose 75% of the time, we will be on IRC while playing, and I will never be #1. I look forward to seeing you on the WiFis.