Gundam Seed was a very bad experience for me. I've watched parts of Gundam Z (long time ago, but gave up looking for sub'd episodes), Gundam Wing, Gundam X, Gundam 00, Gundam 8th MS Team, Gundam 0080/0083
When I talk about Gundam Seed, I'm also including the sequel to it: Gundam Seed Destiny as well.
1) Weak Story. I know that the story of Gundam series was not the strong point of the series but Seed's story felt like it was designed to just get-by so that it can show high-powered good action for the younger kids. It was not as political as a lot of the other Gundam stories (which I'm not arguing is a good or bad thing) but if your story is not very political, you better have a good social story. The story is rather dependent on human engineering issue: Naturals and Coordinators. It just doesn't work.
2). Bad Main Character(s): Yes, I'm arguing that both Kira and Shinn were pretty bad main characters. Why? Shinn was driven by emotion and often immature, but honest to his feelings. I could somewhat relate only a little bit with him. Kira, on the other hand, was this incredibly overpowered superior character that also seemed arrogant to me. In season 1, when Kira kicks Sai after stealing his girl, I've lost all my respect and attachment with Kira. I've also hated the fact that Kira would often cry in front of the female characters to get their attention. (At one point, he did it almost about nothing emotional, I still can't remember the exact episode.)
In other Gundam shows, the main character somehow "works" his way to becoming powerful. He trains or he just progresses slowly. This is lacking in Kira, especially during the first few times he pilots Strike, he takes on Athrun's gundam as well as Athrun's teammates. He comes in and decimates everything almost the entire show.
Very little to no character development for Kira + Shinn. Shinn never matured up and Kira turned from arrogant (season 1) to emotionless (season 2)
I don't even understand why the author bothered to include Shinn in Season 2 if Kira would overpower Shinn and save the World.
3) It was way too predictable. Perhaps Gundam series is suppose to follow the tradition of the male boy character saving the world and marrying the princess but at least other Gundam series had some sort of their unique bland in their shows. For example, the only time I can remember Kira ever losing is that one battle with Shinn in Season 2. I always knew Kira would reign victorious or come flying down and save the ship. And the plot just builds up to make it obvious that Flay will die.
4) Did not have a good message. Yes, we are told that Kira is a ultimate coordinator (basically a superior human) and Shinn is just a coordinator. The fact that Kira gets labeled as an 'ultimate coordinator’ and makes Kira beat everything just gives the subliminal message that “superiority beats hard work” Hard-work is what Shinn is because he wasn’t blessed with superior ultimate genes or an overpowered gundam like Kira’s Strike Freedom. And when Kira takes down Shinn, it just tells the viewers that "People who are born as superior / ultimate will win in the end"
5) Was not exciting. This might seem like a weak argument but it ties in with the "too predictable" argument. Because we already assumed that Kira would win / save everything, it made things so much more boring. If our main character was someone weak, and a character like Char or Zechs existed that would be a temporary protagonist, and would save the day instead, it would make the viewers much less expectant of the main character. But sadly, we saw him as the winner before the battle ended which killed the excitement. In Gundam Wing, you're about to shit your pants when the colony is about to crash on Earth. Because it actually made you feel like it might happen or that the show really convinced you how working for your ideals helps you become a better person. Seed did not have such attachments.
6) Lack of proper villians and support characters. Athrun was hyped in the beginning to have a major impact because a ton of flashbacks were about him and he was the best friend to Kira, but he just died off as unimporant through the end. He was just a guy to take care of Cagalli and friend Kira. He had so much potential too.
Lacus seemed like so un-human and felt like she was soley there just to be the main character's love interest
Rey Za Burrel/Durandal sucked as villians. Although their views differed from Kira's, the last battle between them just seemed too forced. There was no build-up that it was destined for them to battle. You don't even have a proper villian, Durandal didn't even battle with mobile suits. In Wing, you can feel that emotion and that desperate conflict of ideas between Hero and Zechs. Even Gundam 00 had a better villain.
It's been more than a few years since I've watched Seed so I might not remember a lot of things. But my argument still stands