Yeah, 3G is nice. Paying money for a spotty connection and very limited data use is totally worth it. /sarcasm
Anyway , If you're looking at buying a Vita, you should have at least five games you'd like to play for it before your purchase. That's my way of deciding whether or not I should buy a console.
Gravity Rush, Persona 4: Golden, Uncharted: Golden Abyss, Wipeout 2048, and Rayman: Origins are games that I believe warrant a purchase. Disgaea 3 is another, but that can be a very niche game. Of course, you still have the entire PSP collection on the PSN store, so you should be set if you have a large enough memory card. (Which is required by the way, so you better get a large one if you plan on investing a ton of money into the Vita.)
Also, if you plan on using your Vita often, I can highly advise that you purchase Playstation +. It's an awesome service that gives you free games every month. It easily pays for itself.
Edit: From what I've been hearing, AC: Liberation isn't a very good game. Very spotty with graphics, half-assed multiplayer just to make a quick buck, and so on.