It's not going to be more than $299 is my guess.
I don't see what the gimmick is that some of you are talking about. I suspect the sliding off controllers might not be used much, but everything else seems pretty solid.
When you're a company that has stepped out of the power race, you have a few options. For the Wii they went with low power, small form factor, and a hook (Wii mote). It was quiet, didn't use much electricity, and games were cheap to make for it, etc. This appealed to the Japanese and a lot of casual gamers. The Wii U tried to be more hardcore and failed at it.
I think they finally found a good solution with this system. It's not super powerful in pure computing power, but the the chips it's using are modern so it can run modern engines (Unity and Unreal 4). Also, because it's low power, it can be portable. I see this as a pretty fair trade off, honestly. Then again I've always loved portable games. I play my 3DS more than anything (cept maybe my PC). So this shit is right up my alley.