First off, a lot of people called this series slow and boring. DO NOT LISTEN. The first few episodes are building up the story for the later episodes, which will have you on the edge of your seat at the end of almost every episode! It especially picks up at the second season with some epic battle scenes and some tension-building political and economic dilemmas.
I did have a few problems with it though. For one, a few of the characters came across as whiny and annoying, namely Saji, Allelujah, and Feldt, although this might be because it was the dubbed version.
Also, although the last 10 or so episodes were incredible, it became increasingly hard to discern which Gundam was which, especially in the finale. I had hardly no idea who was still alive until the "epilogue" scenes.
And, oh yeah, the animation? Absolutely astounding. Probably the best I've ever seen