Supposedly, Sony is working on a way to play UMD games on the Vita, too. So it looks like it MIGHT have full backwards compatibility after all!
It does have a touchscreen, though... but I don't think it'll be overused, like it is in many DS and 3DS games. I'm pretty sure most hardcore titles will use it only in very rare instances, if at all. I mean, the system boasts dual analog sticks too, so a lot of developers will likely focus on that. (: