The memory cards are both proprietary and expensive, and you'll fill up one of the smaller 8 or 16 GB ones fast, so look for a good sale on the higher capacity models if you intend to have your Vita be primarily digital-based.
They released a newer model of the Vita that uses an LCD screen rather than OLED, but as far as I've heard it's fine. The older models come in Wi-Fi or 3G, but the 3G is only compatible with AT&T's data plans and not really worth any extra you might think to pay for it, but it doesn't affect the system in any significant way if you get one in a bundle or something.
I actually like the system quite a bit, their recent push for indie games as well as the fact that a lot of the more niche Japanese stuff ends up on Vita rather than PS3/4 makes me happy I own one.
any of yall play Fire ProWrestling D for the Dreamcast? its my favorite game and the best pro wrestling simulator ever created. if you havent played it yet, go get it from ebay or unless you live in japan you can get it out that way.