Not going to say much really as this is a very short OVA but in short this OVA is average at best or very bad at worst. It have some potential to be interesting based on what it's trying to do but because this is a 3 episodes OVA and only two follow the main story (which we get back to this later), all we got is a very rush story line which feel wasted and make you wonder why make a sequel of this show.
The main story I can gather in the two episodes is two year have past since the incident from the TV show. A new creature was produce in the US which didn't use the same power that was produce in the original show. The original team, Terrestrial Administration Center, who stop the problem are back together to try to stop the new monster with the help of a new side character name Valencia. That's the main idea of what happened in the two episode which isn't very special to start. Unfortunately, this won't get any better from here. They do try to explain a bit of the new monster that was produce in San Francisco but it's very brief and only inform us based on discussion during characters in the show. This does explain a bit of how the monster was produce or how it get to US but it didn't go into detail of other questions which never explain in the OVA. This is sad the final episode for the OVA is literally a filler which some fan service spice on it. If the final episode was use to explain some more of how the new monster was create and the reason for it (while at the same time try to have some sort of character development) this OVA might be okay and this go to my 2nd issue with this OVA which is the character development.
The character development is really nonexistent to tell the truth. The development between Momiji and Kusanagi is literally zero. It look like they was some development during the two year spans from the TV show and this OVA but this drop like a rock when you're watching the OVA as it look like it goes back to same issue from the TV show (Kusanagi do love Momiji but don't want to hurt her, Momiji want to express her true feeling but can't because of Kusanagi rejection, rinse and repeat). It literally tell the audience that nothing have happened between them which is suck and nothing much happened during the OVA until near the end when both come back together once more. As for the rest of the side characters, they're back and look like two of the character did have a relationship but break up. Even so, those character development is also limited to the bare minimum.
The only thing new is the new main character Valencia. She is literally the same as Kusanagi which have the power to change into full aragami. Unfortunately, with two OVA episode, she have very limited character development which is sad as she have some potential to be interesting if this OVA have more episode in it. All we have some a very general basic idea of what she is and how she got her power (which you find out near the end) and also become a generic triangle love at Kusanagi between Momiji (which isn't really a triangle love but a misinform idea from Momiji ).
Even with this, they is a small positive. The animation is a but better than the TV show mostly because this is an OVA. The character animation look better. Unfortunately, this is the only good thing to say in the animation. The rest is okay to meh for the most part and they isn't much detail animation to look at in the OVA.
For the music, it's okay and work but very forgettable to tell the truth. The voice character sound like they're back for this and match like the TV show which is okay I say.
Overall, this sequel of Blue Seed have quite a few issue and it all come down to how short this OVA started. If they use the one filler episode to go in depth of the story and character development, then you might have an average to okay sequel. What we got is a rush story with little development of the character to the point you don't really care what happened. The action scene is okay but not too interesting to watch. I would avoid watching this OVA as they isn't really any value to watch this unless you're a fans of the show (which won't make sense to watch as you're not really missing much from the start if you don't watch it) or you don't mind the fan service that was shown here. Avoid it or only watch this if you have too much free time in your life and need something to feel like you're wasting time watching.