I've put a bit over 13 hours into Musou Orochi 2 Ultimate this past weekend. Used the recommended teams for the first few hours, but once I got Sun Shangxiang unlocked, that extra ground R1 attack was too good to let go of, and she pretty much stayed on my team to bail out the other two characters or to clear out generals in a hurry if needed. I think she's already at level 70. Currently using an all Ninja Gaiden/DOA team consisting of Hayabusa, Ayane, and Kasumi. The extra features are nice- everyone has a new air attack with R1 and you can someone the horse to you and immediately start riding by holding up on the d-pad, similar to DW8.
I double-dipped on the game and have been playing it on both PS3 and Vita. The Vita version is a great port, but does have some noticeable downgrades. It seems to be running at a lower framerate (although this keeps things more stable), there's noticeable missing detail and less enemies on-screen, and something just looks weird with water (screens below), but overall there's really not much to complain about it.
Some screens of the Vita version:
Here's the water visuals I was talking about. Basically when there's no lighting, water is dull and lifeless. It looks pretty bad. When there's lighting of any kind, then it looks better and is animated. I can't tell if this was intentional or is a glitch of some sort. The two screens from the same area.
And for comparison, here are some screenshots of One Piece Kaizoku Musou 2 on Vita. It looks cleaner and sharper in comparison and I think is the more-impressive port.