Looks like a decent concept that blends home and portable gaming pretty well. I like the two-Switches-syncing up concept. I like the JoyCon idea, even if that stick placement is questionable. Now for this important part:
How the **** do you market this thing to kids?
Sure, it looks sleeker, but that probably means its more delicate, too. That clipping system doesn't look kid-friendly in any way. And of course, if you expect to entice the handheld market with the Switch, how are you going to price the games? I see lots of developers there that excel at the 35-40 dollar price range, but if you're merging your portable and home development studios, you need to know that pricing a game for a home console is going to get risky. If they were to lower their game pricing to 50 bucks, it would make the Switch seem infinitely more competitive in the market space than Sony and Microsoft's offerings, and create some goodwill for portable players.
I think that the Switch as a social and portable gaming device sounds fascinating, but it's going to need a lot to work in execution. Those controls and their power source, as well as the screen, for example, and the business of actually getting people to buy into this thing again. It's just too risky, and we've seen a big list of developers be on-board for Nintendo products in the past only to abandon ship when units don't move. Right now, I don't see any reason to think this thing will be a success.