I've been playing this all weekend since Friday and love it. I got it late Friday night due to an Amazon mishap. I preordered two weeks prior to release and then on Friday Amazon said it "shipped" but according to UPS tracking, a label had only been created. That night I decided to call Amazon. They said it was lost and offered either to replace or refund. I took refund and got it from eShop.
This game got damn near everything right, and even topped MK7 for me. The handling feels different that before, but a good kind of different. The level of graphical detail, is incredible, where you even see details like snow and dirt on your tires.
Most of all, the items are ACTUALLY BALANCED FOR ONCE. Blue Shells aren't that common, and even then you can hold onto a Super Horn if you expect to get to first place soon. The item holding is balanced, which is definitely a change for the better. That stupid fucking lighting cloud from MKWii is GONE (Why did that thing even exist anyway?), The new items are great too, I think the Boomerang is quite nice. I also like the little changes like actually showing how much time/uses are left on multiple use items, such as the Golden Mushroom or Piranha Plant.
Online is awesome, I've been playing on the NeoGAF Race |OT|. My Mii's name is "Matt" with a green shirt and brown hair.