I'm at PAX South right now and tried the Switch. They had two lines. One was for an open area where you had like six games, the other line was for BotW. I got there super early and into whatever line I could which turned out to be the BotW line.
My impressions on the Switch:
It's surprisingly comfortable. I thought the b button would interfere with the right analog stick but I didn't have many problems. But it was close, someone with bigger hands might have a problem with unintentionally pressing the right analog down as you select B.
The controls click into the tablet and controller dock but don't have a reassuring thunk as you do it, it's more like the click of a cassette player being closed if that makes any sense.
The "dpad" is going to be a problem for some people. The buttons are spaced too far apart, it's not a proper substitute so don't expect to play a lot of retro games on this without the pro pad.
The BotW looked okay. I played it docked but towards the end I was allowed to take it out and use it portably. Once I had it docked I was convinced this is a Zelda that most people will play portably. It's pretty impressive on the small screen but on the tv the game looks terrible. There's tons of pixelation around the characters and textures close to you look blurry. But I think 3ds games look like trash so some of you that are used to those might not even mind it.
My impression on BotW:
Great game, it's fans won't be disappointed. The controls felt alright but it noticed that they do change according to the weapon you're holding which could be a good or bad thing. When I used a heavy axe the controls went I to a more tank-like scheme and I did get turned around and had to pause to reorient the camera and controls. It was a nice 20 minute or so demo. It seems the world map is divided into sections that you move around with using teleporters. I don't know if you can freely walk into other sections or if the teleporters just played a specific role for that part of the game/demo, it could be that each section of the map is its own enclosed area from the look of it. Doing a rough estimate of the distance on the map I traveled and the map as a whole, I think the map is about the size of the first two islands in GTA3.
I'm still not convinced to get the Switch on day 1. But with this demo I think I will be getting one eventually.