The console itself is fairly decent for it's size, it would be interesting to see whether long-term hardware issues will arise out of shrinking down such high-performance components. All of the tech demos seem very smoke-and-mirrors at this stage; when the Wii was revealed there were real demos with playable games that people could pick up and enjoy. Overall the hardware feels current-gen, and with MS and Sony already planning their next consoles, it won't be long until Nintendo is again at the back of the hardware rankings. No media playback seems like a bit of an oversight; it uses a proprietary disk format, and there is no mention of media playback, except Youtube integration. Seems it will follow the same path as the Wii did with DVD/media playback.
The controller seems strange; you can use it in several different ways, but it seems to be optimized to a tablet-type usage scenario. The placement of the shoulder buttons seems very awkward with the size and shape of the controller. As i said, it just looks like they've tried to incorporate everything including the kitchen sink at the last minute, with no _real_ use-cases or target applications.
In the end the biggest disappointment for me is that Nintendo hasn't addressed the areas it admitted it failed with the Wii. Not so long ago they said they knew they had failed to engage developers on the same level as MS and Sony, and they had failed to create a healthy online ecosystem. Their announcements at E3 haven't addressed either of these failures, so I can only assume that they are still working on a solution, or they are going to continue with the same strategies that they have used in the past.