The battery life shortfall will be a huge problem. So will the inevitably half-baked overlay UI to cover up Windows 7's shortcomings as a touch-enabled OS. In the end though, I think that the Slate and the iPad are targeting different markets. The HP offers the same computing experience you can get on a laptop or desktop with touch input grafted over top. The iPad offers a new experience that focuses on getting the user to his/her content with the least amount of fuss. So its entirely likely that the Slate and the iPad could be successful catering to different segements.
Or the HP could fall flat on its face, like every single
Windows-based tablet before it.