The dialogue struck me as quite good, actually, especially when you consider how bad games like this often are. It's passable at worst, but seems above average most of the time.
Checking out the PSP version now. Seems roughly the same, just a bit less pretty. But it really does make it seem even more odd that no PC version has been announced, because the PC demo and the PSP game are both very different yet still consistently well done it seems like. If you're going to take the time to develop a very nicely working PC version, why not offer it for sale? I mean, we sort of guess they'll be announcing it at some point, but it just seems like it should already be up and running.