I see that Pocketgamer have also reviewed Super Monkey Ball: Banana Splitz on Vita giving that a solid 8/10.
http://www.pocketgamer.co.uk/r/PS+Vita/Super+Monkey+Ball%3A+Banana+Splitz/review.asp?c=45104
I wasn't expecting much from Monkey Ball following Sega's attempts at running the series into the ground but if this is a return to form, it may well be another game on the to buy list.