It's fantastic that people like to throw around phrases like "best Gundam series ever" in reference to one of the worst, and many -- but, granted, not all -- admit to having seen very few other Gundam shows.
Nothing in Gundam SEED is new or original. The Natural vs. Coordinator conflict may be a bit closer to real life, but at its base it's not much different from Oldtype vs. Newtype. Everything in this show, right down to some minor details, can be traced back to some past Gundam series. It's one thing to reference old shows here and there, to pay them homage like that, but it's something else entirely to just build a new show completely out of old ideas. Actually, I should clarify. There was one original idea in this show, but it was promptly dropped after episode 20 and never acknowledged again; according to interviews with the show's director, there were *never* any plans to take it anywhere, it was just thrown in for no real reason.
The characters aren't very good. There was one character in the show I liked, and -- surprise, surprise -- he bit the dust. Other characters ranged from underdeveloped to boring personalities to downright irritating, and all things in between. Furthermore, the show's masked villain, Raww Le Klueze, is easily one of the worst Gundam villains ever. He's just a psychotic nihilist and nothing more. At least past villains had some sort of motive in whatever they were trying to accomplish, but this guy just wants to destroy for the sake of destroying.
The character designs are absolutely awful. Character designer Hisashi Hirai should put out a book on resourcefulness, because that's about the only way I can see that he still has a job. He can only draw one or two different faces and two or three different hairstyles, and he puts them together in various combinations with various different colors to create an entire cast. No joke here, Japanese fansites were actually taking screen captures from the show and replacing the hair of characters in the scene with that of other characters, with hilarious consequences. After all, they all looked exactly the same, so you couldn't even tell the difference if the hair was replaced.
The show hosts some of the worst mecha designs ever to grace the Gundam franchise. There are four in particular, Gundams which appear late in the show, which are just horrendous. The rest of the designs in the show range from decent to bad, and many of them are just taken from old shows and given some extra junk on the backpack (anyone else have the feeling they'd seen the Freedom Gundam before? Yeah, that's because it was originally known as the Gundam Double X back in 1996).
The animation is pretty bad too. Ship and mecha movements are all done with computers, and they look terrible. Character animation isn't quite so bad, but people could stand to move a little more. They float down corridors stiff as a board, not moving their limbs at all. This problem isn't unique to SEED, though, as it occurs in several other Gundam shows as well.
With the exception of one track which was only played twice, the background music in the series is pretty bad until the last ten episodes. At that point, they suddenly introduced a few new tracks which were actually pretty decent. So the music is a mixed bag -- most of it's not very good, but some of it is all right. The openings and endings were much the same; early songs were bad, later songs were a little better. The second and third endings (known as River and Find the Way, respectively) were both quite good. The third and fourth openings, Believe and Realize, were decent. However, the first and second openings, Invoke and Moment, and the first ending, Annani Isshodattanoni, are terrible, bad, and below average, respectively.
Overall, SEED wasn't the worst Gundam series ever. It is, however, nowhere close to the best. If you want to see a good Gundam series, a real contender for the "best Gundam series" title, check out First Gundam, Victory Gundam, or Turn A Gundam, but steer clear of Gundam SEED.
