It depends on who you ask. You talk to an IBO-fan, you'll hear how it's one of the greatest Gundams ever with a great focus on the politics of the setting. It focuses on the characters, making the audience care about them. Though few in number, the action scenes are also top notch and are treated like a reward.
You ask someone like me, I'm going to say it's overrated. There are excessive amounts of forced exposition, done in ways that make the characters look like idiots. It's repetitive enough to make a drinking game out of, the politics don't hold up under examination, and the series is ridiculously telegraphed which ruins any sort of surprise. The actions scenes are visceral-looking, but beyond that can be rather underwhelming. Mikazuki is more a side-character than a protagonist.