So my complaints so far... There's no day 1 cross-save, and I'm betting they're planning on patching Borderlands 2 for the PS3 next week with the game's official launch, which is unfortunate, because I want to be level 50 now so I can test out the end-game.
And I just started the game up, and the back touch screen isn't working at all. So I have to either play without being able to sprint or melee, or I have to restart the game and deal with the loading screens, which aren't bad, because they're about as long as the PS3 version's, but that's still pretty bad.
Also, I'm using the original Vita (whatever it's called), and was having no problems with back touch screen controls until now, where they're not doing anything at all. When they are working, they're great. The low enemy count is noticeable, but I'd have to get further into the game to be able to count it as a flaw. As it was, I thought the original game was unbalanced in favor of the enemies.
Edit: Also, I find it really odd that there's all these touchscreen controls for navigating the menus when all the text is extremely small. It's like they meant to scale it all up, but didn't.