Ok, I'm gonna skip the obvious parts that you've probably already read in other reviews. This was meant to be a longer TV Show, we know.
Actually, considering the facts this could've turned out way worse. That doesn't mean is that good.
I'll start with the negatives, and then I'll try to end on a more positive note.
The story is very messy. Motivations are not clear and the villains are very cliché. Just your average "hurr durr imma baddie i'll kill everyone". Pacing is also an issue. This suffers the same problem as CCA, where Tomino probably thought we would get bored if we didn't get a mech battle every 20 minutes or so. This obviously doesn't help in the structure. Instead of scalling up things to a climax, the final showdown just comes and plays out like every other fight in the movie. -pew pew, things blow up, mechs blow up, someone irrelevant dies.-
The characters are also wildly underdeveloped. Instead of presenting a couple of secondary characters we'll get to know a little bit, Tomino loves throwing out 6+ characters that will barely get any line at all. There's a plus if there are very young children just because. I think this movie confirms my beliefs that Tomino isn't really a good writer/director.
Now to the good parts.
Even though they are underveloped, the characters are likeable. There was a point when I was wary of a character doing a stupid 180 like Quess Paraya in CCA, where a neutral character becomes friendos with the murderous genocidal baddies just 'cause. However that did not happen here. I was very happy about that. Maybe not having horrendous hateable characters that aren't meant to be that way is not much of a positive. But with Tomino, *ZZ and CCA flashbacks* you can't take that for granted.
Now for the real compliments. I have two. This has one of the best animation cuts in all of the Gundam series. There were moments where i could swear they were rotoscoping everything, but then you notice some details and you know everything was done traditionally. The attention to detail is amazing. Something as simple as showing the hand of a Mobile Suit malfunctioning and spinning around like crazy just adds so much and grounds the film in reality so good in many moments.
And my biggest compliment:
Damn.
What a great opening sequence. Even if you don't want to see the movie after reading this review, do a favor to yourself and watch the first 15-20 minutes. I think this is the most horrendous and gut-wrenching depiction of war that doesn't resort to very graphic and explicit imagery. I felt genuinely disgusted at myself for watching these scenes as part of "entertainment".
A plus: Apparently the story and the characters get really fleshed out in the manga Crossbone Gundam. I have not read it myself, however i've heard it's quite good.
