So I went to see it, left after an hour after playing Zelda, Splatoon 2, MK8D (came #1) and the marble game.
The switch itself is nice, smaller than I thought - it's definitely portable. And the screen is decent, shows off small details well. Perhaps a little bit washed out but maybe that was due to the brightness, can't say. Joycons are so tiny and neat! And the "dpad" on Joycon isn't that bad, very easy to press in and not that far apart from each other.
Pro controller is
almost perfect ergonomically. Dpad is too stiff on it, to be honest, I think I preferred the joycon d-pad. It is seriously stiff. But I can't get over how itself was actually super comfortable to hold. Crazy.
Zelda framerate ain't great... feels a bit slow and choppy like OoT n64, maybe a tad better. Apparently people are saying the final release version is better than the preview build - I'd hope so!
MK8D was MK, though I noticed you could actually hold two items, which I remember not being able to do in the WiiU version for some dumb fucking reason (correct me if I'm wrong). Feels much more like MK because of it.
Splatoon 2 was neat. Attacking is a bit slow (I used the roller after hearing on gaf how OP it was

it was my first time playing - actually our whole team used it - and won by quite a bit).
HD rumble is pretty good - you get finer sensation for small rumbles and can tell that apart from bigger ones quite easily. Might be good as a resistance kind of thing with Super Monkey Ball or Kororinpa.