I'm copy-pasting this post for the person who wrote it and who asked me to post it here, since he can't register to the site. First of all I apologize for any english mistake, I'm not that good with it.
I played the demo at a private Nintendo press event. There wasn't many people around, so I had the chance to play this a lot, like 15 times at least. In the video I tried some "strats" I came up with thinking those were the fastest routes avaiable for the 3 demo tracks.
My comments follows a random order:
In the demo there were 6 "parts" of costumization avaiable. It wasn't possible however to change them: each character was given only one combo.
The parts were:
Standard Kart
Standard Bike
"Tornado" Kart (I don't know how to call it, it really looks like Tails' airplane!)
Normal Wheels
Slim Wheels look alike
Monster Wheels look alike
And this is how the various parts were combined for each character:
Mario: Standard/Normal
Luigi: Tornado/Slim
Peach: Bike/Slim
Yoshi: Standard/Normal
Toad: Bike/Normal
Koopa: Standard/Normal
Wario: Standard/Monster
DK: Bike/Normal
Bowser: Tornado/Normal
Daisy: Standard/Monster
Waluigi: Bike/Monster
Toadette: Tornado/Monster
Now some impressions I had by playing each character and some of them multiple times:
Tornado seems to be the kart with the most handling, in the water too. Even using Bowser I found myself to have more handling than with other parts.
Monster wheels had the worst water handling. Lower handling than normal even on normal road. This time Monster Wheels DON'T keep their MT charging when going offroad. Tried many times on various grass/mud fields.
Slim wheels seems to have the higher handling out of any parts. Luigi, which also had the Tornado Kart, seemed to be the character with most handling. They worked great in the water too.
Graphics are awesome (I don't have a WiiU/HD console). Every track is really detailed. There are also a lot of new animations. During tricks, for example, Peach does some cool ♥♥♥♥♥y moves. When throwing a banana forward, it spins in a really cute way!
Drifting was the oddest thing of all. I think it's a bit worse than MK7 but better than MKW. Seemed like a mix of the two. But you really get used to it after a few games so it's just fine like it is.
I found the glider to be harder to move around than the standard one in MK7. I felt it also to be very slow. That's why I couldn't try some glider bounces around, handling and speed were too poor. There were no points that allowed me to try a glider boost, if any.
However I found something that may be interesting: By tricking the blue ramp you'll receive a trick boost when your glider lands. Now, I tried to close my glider with B and... the boost was still there! So I tought that this thing may be a way of speeding up some glider platforms (like the one in the first track, which is in the middle of it so it's pretty "useless").
This is the "formula":
Trick>Fly for a few time, close to the ground>B>Boost
It WON'T work if you do:
Trick>Immediatly press B
To be honest it didn't work just once with me, but that time I did it really quickly. Maybe you have to fly a minimum time to keep the boost, who knows.
This tecnique may be totally useless, but who knows! I do it (really bad 'cause I'm a noob) in the video.
By going reverse on the track, after some seconds lakitu picks you up like when you fall out of the track. You can see this at the very end of the Boo Mansion if my video.
Gravity was a huge relief, since everybody were kinda scared by new physics and the spinning thing (me too). Driving is really the same as on normal track for every kart, it looks like it does not have its own rules like water. Spinning slows you down a tiny bit, but you get a boost equal to a blue MT right after (both player that crashed) that compensate for the speed loss. Or maybe it will make you gain something...
Drifting>Tricking a ramp>landing with the MT still on charge is possible only by tricking by shaking the controller, since the other trick button is R.
There's no A+Drift turnaround. R hops when performed holding a direction will make the kart turn greatly to that direction, so with a few hops you can easily set the new trajectory.
Water seemed slightly bettere in handling than on MK7. Only Monster wheels seemed to be at a disadvantage.
Shells have less hitstun. Bananas are really powerful. Reds seemed to be more stupid than MK7 ones (still light years better than the Wii ones).
I got Fire Flower a very few times, but spamming it repeately seemed not to cancel previous shot fireballs.
Delayed MT seems to still be there. Crashing into a wall during a red MT boost without losing speed is still in there too.
Charging a MT with automatic takes really really long. For example, the very first turn in the first demo track may charge only one Red MT near its end.
Map on tablet is really unconfortable. Items are also very small to see. You can only see the map with the "shape" on the track and not the one that focus on the specific section you're racing on, with the items on the ground and stuff.
When hitting Goombas they won't drop a shroom. Instead they fly around like crazy. Too bad they don't cause damage to other racers.
Game looks very good I'm really hyped. I hope those info were useful and interesting.