I will keep this impression short as they isn't much for me to say. Blue Seed is an okay show. It isn't the worst show I have watch in animated category but it isn't the greatest I have watch as of now. It's kinda in the middle. It have enough stuff to make the show entertainment to watch but they're quite a bit of things in the show that drag on a bit too long which make it harder to keep on watching the show. I won't be surprise if people stop watching along the way because of this issue.
The story line have a deep Japanese legends which is kind of interesting. I won't go into it too much as it will spoiled quite a bit of what will happened in the show but here is the main idea. They is two force is happened in the show. On one side you're following the main female character, Momiji, and the government agency, TAC, who main purpose to protect Japan from danger of this aliens force call Aragami. On the other side, the forces from Aragami are trying to destroy Japan for their crime with mother nature and trying to recreate a new Japan where only them self will be the victor while the human race will fall and turn into plant life. In the middle you have Kusanagi who is in charge to safe Momiji life while at the same time fight against the Aragami force even though he is the same breed as Aragami (basically, an alien siding to the human side).
They're more things happened in the show which is also important like Momiji have actually a twin sister name Kaede who both of them are actually a descendant of woman who need to sacrifice to safe the life of Japan. Unfortunately, Kaede die in the 1st few minutes in the 1st episode but she will become an important person if you keep watching the show.
Like I say, the story is not bad and actually interesting but it got stumbled a bit at the beginning when they first use monster of the week style episode. You notice this in the 1st half of the show which is a hit or miss depend on the audience. They is some plot development during the 1st half but this change quite a bit in the later half where the plot of the story start to move and you start to understanding of what is happening in the show. I guess you need to stick with the show quite a bit to get to the juicer part.
As for character development, most of the development is coming down to Momiji and Kusanagi. For Momiji, she act as someone who don't settle as a damsel in distress but as someone who want to be out there fighting and doing her part to help her friends in the TAC and Kusanagi. For Kusanagi, he is an interesting character as he have feeling toward both Momiji and Kaede. Even with the feeling with Kaede, he eventually stick his love with Momiji once he realize how special she was to him.
For the rest of the side characters in the show, they have the basic character development and some of them have a backstory which help fresh out a bit. Even with this, they're not too interesting to look into.
For the animation wise, it look a bit dated like it have this late 80s look then when it was release. This get a bit better as the show process and eventually look okay at the end. Not really a downer for me to tell the truth.
The music of the show is okay and work well in the show. It didn't catch my attention too much to tell the truth and this is weird for me as the composer is Kenji Kawaii which is someone I like to listen to his music. Might not be his best score when I listen to.
Overall, Blue Seed is a okay anime to look into mostly because of the interesting supernatural elements and story line. The shortcomings from the show is something you need to bear with for the 1st half but once you get through, it will get better and interesting.