I don't see any reason why it would behave differently than a regular Vita, and thousands of people play imports on that, including myself.
Basically, if you are playing cards there is no difference in region for the hardware.
With all the PSN stuff, including promo codes that give you rainbow colored M16s and shit, they are region locked. Switching between regions requires that you have an additional memory card and when you want to switch stores you have to change memory cards and do a system reset. It's a pain, much worse than PS3, but not a big deal.