I can't imagine it being any good on Vita; game just doesn't play like it would work on that interface.
Terraria was fantastic on the 360(superior even to PC, *control wise), I imagine if they do the controls similar to the 360 with the benefit of touch it would play great.
Also: Draft of patch notes - Linky
edit:
Did not mean to come off hostile :3 . My gf and I enjoy the 360 controllers more than PC but our first experience with terraria was on the 360, so that may be why we prefer it. I totally understand why someone wouldn't enjoy playing it if was the other way around.Hmm, from my (albeit limited) experience with the 360 version of Terraria I'd disagree. But if you enjoyed it then no doubt others could.
EDIT: Nom, patch notes!
Think about it though, SB on a mobile platform would be glorious, so all they need to do is make the controllers serviceable.