Got my hands on Killzone, Dragon's Crown, and Batman (Vita versions). Killzone and Batman really impressed me.
Killzone played really smooth, I think I had one instance where there was a hiccup, but overall very smooth. Tried sp and mp (infrastructure only up to 8 players). Melee was weird and annoying, hit triangle and then you have to do a series a swipes that display on screen.
Batman demo was linear. Fighting felt just like the console Batman games. I got stuck on one part where I was forced to throw the batarang, but the enemy kept dodging it.
Dragon's Crown gameplay just didn't click for me, but loved the art. I tried Elf, Sorc, Dwarf, and Amazon. Elf felt the most fun. Dwarf just felt too slow. I might still end up getting it, might be more fun co-op.
Overall Killzone and Batman felt like they will be solid purchases when released.