I can only speak for PS2, but for the story, get both AoTI and the original PSU, but if the offline's great, online is most likely..... well, too great .
And I'm starting story mode offline (Again) I hope I get access to ep3 though.
But it works better than it did on the PS2. Can I transfer my character data over to online? Oh, and weren't there cheats to play as Leo or maybe even Karen?