First of all, the show's animation and art is old. For some this isn't really a problem, but for me it took a while to get used it. It's not atrocious by any means, but the art and animation don't add a "wow" factor to the show as a whole so don't expect beautiful spaceship battles and eye candy.
If you can deal with the old art and animation, you're in for a treat because the story and character development is fantastic. The author knows what its doing with its characters. Most of the main characters have motivations that are complex and often challenged; they must endure trials that make them question and slightly revalue their beliefs and their character grows as a result.
This development is intertwined with the complex and engaging story. The two main groups fighting in this show are the Free Planets Alliance (FPA) and the Galactic Empire (GE). Neither side is necessarily evil, and main characters fall into both factions. The two sides fight a bitter war that kills billions of people and takes the lives of some characters we come to enjoy. Since neither side is evil, it creates a rather interesting scenario where it's hard to cheer for a certain side to win, because that would mean forgoing some cherished characters on the other side. It's far more engaging because it forces you to constantly evaluate the motivations that each character has, because it's not so simple that you can write off one side as just "evil for evil's sake".
In depth character motivations make for interesting and coherent decision making. For the main characters, you get to see the choices they make and their justifications for them. There's rarely a moment where characters make out-of-character decisions for the sake of plot - it's always related to their inner ambitions and motivations. You even get glimpses into the motivations and decision making behind many side characters, making them more than bland tropes (Oberstein!!!)
So far I've only mentioned the GE and FPA as being the two main sides that fight each other in this show - well I was being a little bit misleading. They are the two sides that have actual characters. The Earth Cultists are a third group that become a major nuisance to either side in the latter half of the show. Unlike the FPA, and GE, there are no characters with in depth and complicated motivations in this group. The de facto leader of this group is De Viller, who's motivation is to cause chaos and obtain power. He name literally sounds like "Devil" and he is the embodiment of pure evil in this show. While this doesn't ruin the still morally grew and complicated conflict between the GE and FPA it takes some engagement out of it because now there is an objectively immoral character thrown into the mix.
This wouldn't be so bad if De Viller's actions weren't so impactful. The climax and finale of the show is entirely manipulated by them. To have such a bland and underdeveloped character to take the reins of the show is beyond jarring and I found myself more pissed off that I really should have been. Another thing that bothers me so much about him is that you don't even see him making any decisions - you merely see the consequences of them. As an example in contrast, Reinhard will make a decision to enact 'x' plan and therefore you see 'y' result play out in the story. In many cases, 'y' doesn't play out completely because there are things that deviate from 'x' plan/decision. Plot points revolving around De Viller skip 'x' and jump straight to the 'y'. Since 'y' is so significant in the end, it's ridiculous that you don't get to see the build up to it, like you do when other main characters produce consequences.
De Viller and the Earth Cultists stopped me from giving this show a 10/10. The ending is still very solid, but these guys still leave a bad taste in my mouth. If you can stomach these guys and the fact that they go against so much of what is good in this show then this will be a 10/10 watch for you. Nevertheless, the characters of the GE and FPA are still fascinating and make this show great.
