Bought it, played MK World, it was everything I hoped it would be. Smooth as butter (haven't seen any slow down/frame skipping), graphics look fantastic (why do some people only think "realistic" = good graphics?), and the music is SOOO GOOD! The remixed tracks from previous titles are done really well, at least the ones I've heard so far.
Who knows how well it will do in the long run, but so far the Switch2 is off to a great start!
I will say that I'm not a big fan of the joycon button sizes, I can already tell its going to give me a blister on my thumb. Waiting for my Pro controller to arrive to remedy that.