I know the word is overused, but the word epic is the best descriptor of this film. Everything about it is larger than life. It's a movie about giant robots fighting giant aliens, and it's unashamed of that. Instead of trying to cram in unnecessary subplots or romantic tension, it simply lets the audience enjoy what we really want to see:
Giant robots fighting giant aliens.
Along with that, it has some memorable characters with actual depth, a vivid, extremely detailed world, and a plot that, for the most part, keeps you on the edge of your seat. Sure, it has its flaws, but I wouldn't hesitate to call it a masterpiece.
I really have no excuse for waiting this long to see it. Don't make my mistake: if you haven't seen it yet, then fix that mistake as quickly as possible!