Yeah, the lack of exclusivity has held me back so far. I mean, most of the PSN games people recommend on Vita I already have on PC, 3DS etc.
I really enjoyed Dragon's Crown on PS3, but ultimately returned it. However, I think I'd have a lot more fun with it on Vita (but I prefer handhelds anyway). Danganronpa looks good, but nothing else is really grabbing my attention yet. Hopefully it will in the future, like the PSP did.