I'm also currently in the middle of playing Chaos Rings II when I'm not playing Dawnguard or Batman: AC (so lunch time and times when it's too late to be playing Rock Band). Squenix had a sale on the first two titles (CR1 and Omega) last Christmas, and they were crazy addictive. CR2 is similar gameplay-wise, but it mixes it up enough to feel newer.
I'm almost done with my first play-through, and it's been a lot of fun so far. Requiring the player to be an utter b-----d is a nice touch which I'm certain will have an awesome payoff further down the line. The actual plot's about as insane as the other CR games, too.
You know, much as I complain about Squenix's pricing tiers, I really would pay $20 or so for a game like this on PSP and consider it a bargain. It's a damned good PS2 game that just happens to be on iOS.
Now if only the voice acting were a separate download. Too many dramatic pauses (some of which are at the beginning of their line and last several seconds, which is kind of confusing when you're expecting to hear dialogue), and it's all in Japanese anyway.