Some more thoughts:
User Experience Video
The Switch is surprisingly one of the best user experience videos I have ever seen, and from Nintendo no less. Nintendo did a great job not just designing a product that can adapt to every gaming use case, but literally showing the transition between each use case in the video.
Home console
Portable console
Spontaneous portable multiplayer (anyone who has used StreetPass on 3DS or Pokémon Go understands why this is awesome)
Local casual multiplayer - what the Wii really excelled at and what Nintendo has always supported on every console
Online multiplayer - a given
LAN party/E-Sports - this to me is very interesting and the Switch synergizes incredibly well with E-Sports logistics while letting players keep their personal settings and avatars in their own tablets.
Ecosystem
The ecosystem debate is an eternal one. Skyrim and NBA 2K are huge additions, and likely aren’t official yet only because Nintendo is legally obligated to wait until after Holiday 2016 to confirm. It is a double-edges sword because Nintendo makes amazing games, so 3rd parties have to compete with them for software dollars. If they get a big install base, more 3rd parties will come. A strong launch seems likely based on response so far.
Recent Resurgences
I’m just happy to see continued hardware and software innovation from Nintendo. Splatoon winning FPS of the year last year proved they still have the magic and talent for new franchises, much like Overwatch did the same for Blizzard this year.
OS/UI/Software
Now that we’ve seen the hardware, I honestly am excited to see how they have improved their software and OS. I was surprised when PS4 and Xbox One launched with clunky UIs. They have now been remedied, but were much more frustrating that the Wii/WiiU minimalist approach. I trust Nintendo to make their new OS a little more potent while still being a breeze to use.