I beat Magus Sisters on my first time. They never had time to use their Delta Attack. Dark Knight's Darkness and Gunner's Trigger Happy are great there as well as Alchemist's Mega Potion.

I really liked FFX-2, and it was a great game, but there are a few things that should be better, IMHO:

1) Many areas are identical to their FFX versions. It's realistic that the landscapes of the places have remained the same, but surely Square Enix could have enhanced those places more?

2) You can't change your camera angles. Usually this isn't much of a problem, but sometimes it's hard to walk around when the camera's zooming to totally wrong places.

3) Not all the mini-games are great. Even though there are entertaining games too and Sphere Break is fun, Blitzball seems as bad as ever and the towers 7-10 are really annoying to calibrate in Thunder Plains.