Like many shows of the era, it is heavily influenced by Uchuu Senkan Yamato. So much so that the plot of Baldios and the original Yamato are basically the same thing, with the only real differences being that the alien race isn't blue and there is mecha action involved. Well, there's a bit more to it than that, especially at the end, but the set up is almost identical.
The story is told at a mostly gripping pace. The first episodes are great and lock you in right away. Things inevitably slow down a bit, but there are some great two parters in there and overall I never felt like it came to a drag. The story is basically where this series is really going to shine. Trust and betrayal are a commonly occurring theme, as a big part of the show is about the struggle of the main character, Marin. He puts himself between a rock and a hard place as he decides to pilot the Baldios and fight against his own people on behalf of the people of Earth. The people of Earth are not very trusting of him though, including his own comrades, as he is one of the aliens. He goes through a lot of mental anguish over this and even goes back and forth between sides a bit. His motives and morality aren't really black and white, and he often succumbs to the overwhelming amount of stress put on him. He makes for an interesting, if not believable lead character, and is less one dimensional than the lead characters in these shows typically are.
The music is fantastic. Being the handiwork of Kentarou Haneda, this is no surprise. Although it's not his best work, it's still very good. His style and signature guitar riffs permeate all throughout the series and truly make up much of the personality of the show. It wouldn't be the same without him. There are great insert songs as well, with the most memorable one being a Isao Taira (Ideon, Bryger, Daiohja) tune. The show was produced in the early 80s, but for the most part it looks (and feels) like it's straight out of the 70s. There isn't much that is remarkable about the art, you can pretty much assume what to expect if you've seen an Ashi/Reed show or any old mecha.
One particularly weird thing about this show is the mecha elements. They are extremely tacked on. This show could easily exist without any mecha stuff, and whenever it comes up it feels forced. It really doesn't come up much to be honest though, and there are entire episodes with no mecha action. The beginning is a bit misleading with this. It feels like they wanted to make the mecha stuff feel important, but ultimately the emphasis put on the Baldios machine is all but completely dropped after the first half dozen episodes. You won't be coming out of this with many memories of the mecha using signature attacks and poses. Baldios certainly looks awesome though.
The production history for Baldios is a bit wonky. According to whatever info I could dig up (there isn't much), this is yet another cancelled series. The show was originally planned to have 39 episodes, or at least storyboards were conceived for 39 episodes. Only 34 episodes were produced, and 31 of those episodes actually aired. When the series was released on video, all 34 episodes were included though. If the movie is the canon ending, then episode 34 is not canon. It is basically a completely different ending, that is simplistic and leaves important questions unanswered. It is probably the result of a rush job/cancellation. The movie does some recap, but essentially picks up at the end of the huge cliffhanger in episode 33.
As for the movie itself, there are already some good reviews on it. It's great, and the best part of the entire experience. The grim atmosphere is at its most oppressive and the harsh reality of what has been going on is finally set in stone, and we watch everything crumble and hope completely fade. It's a powerful ending, and likely one you won't forget. I wouldn't really advise skipping the series if you want the full experience, as the characterization in the movie (recap parts) is weak, and not a very good substitute for the series. The recap parts also feel very janky and random, unfortunately. The new content in the movie though, is all excellent. Lastly, there are several versions of the movie. There is a lot of blood and violence, and it seems that most versions are edited. You'll want to watch the Japanese version if you want to see the original movie.
