I got this game with my Vita and was not disappointed with it. It delivers the kind of experience you'd expect from a full-scale console game, with an extensive campaign, huge open-world areas and tonnes of side-missions and collectables thrown in as well. The main character isn't the best, but she's well-developed and interesting, plus she has access to a wide variety of unique weapons e.g. a poison blowpipe and a whip, which functions like the Rope Dart of the main AC3 title.
The only thing that stopped me giving this game five stars is the presence of noticeable glitches. Aveline will fall off or through things for no reason, the game will occasionally slow down and people will sometimes be seen walking through walls. The last issue never happens with anyone important, however.
All in all, an impressive game.