Button masher at its core
Sound: Nothing to complain about and it fits.
Graphics: Nothing overly spectacular, although for the movies they've actually gone with something a little more High Def than they did in the first in the series. Still nothing major but it's an improvement.
Story & Story Mode: Honestly I'm not all that familiar with all but two of the Gundam series, the developers did make an effort to try and explain the story of the series they chose for the story mode with little summary paragraphs between most missions and better cut scenes. Unfortunately they also chose to use the same series for this mode that they did for the first game. I would have liked to have seen a different story for this one. As for the story in Mission Mode, I haven't really explored that yet so I can't really say.
Gameplay: As I said, this game is a button masher with only a few different combos. The only real variety that comes is when you use a different mobile suit and that's only the animations for the various combos. Enemies, except for the giant mobile suits and "aces" don't usually do a whole bunch.
That's pretty much all to it. As I said it's a pretty simplistic game.