I actually completed an entire game of BF 4 with remote play. In vehicles, the sticks work fine since the sensitivity of the vehicles is naturally low. On foot(after my first tank got blown up), I got a couple of kills, but that's mostly because I had the drop on them. Aiming as infantry with the vita is.... Unfortunate, but possible(I should probably have turned the stick sensitivity all the way down in hind-sight). Overall, finished the game with 10 kills 8 deaths and about the 4th highest score due to objectives. So not bad, considering.
Edit:
Also, I was wondering, is there some way to get party chat to work while remote playing? When you go into RP it closes the vita party app and the PS4 party chat doesn't recognize the vita's built-in mic or any mic that gets connected to it.