Facts you should know that largely influence my opinion: I am a girl and I like shounen ai (boys love).
While this anime isn't strictly geared towards a female audience particularly, I felt like maybe there were certain elements girls might appreciate more than the male audience. The abundance of bishonen is a great example.
In any case, if you're still with me onwards towards the breakdown!
Story: 6-7
I think the story is fair. The other reviewers are right in saying that the story is very trope-ish with a lot going on, but I didn't particularly mind. It wasn't hard to follow, and sometimes I want to indulge in a little guilty pleasure of special MCs, hierarchy climbing systems, bishounen fights and quirky female characters.
But I wouldn't brush most of the story with the same stroke - after all, I've only watched the 12 episodes provided. I don't know if they're going to delve deeper, but from the last episodes subtle clues I can definitely guess we've only scratched the superficial surface of what the story really is.
Art: 8
I really liked the art. The fight scenes were really good, better than a lot of shounen animes these days for sure. I really enjoyed the abundance of colours from the characters appearances, the landscapes, their weapons and so on.
The designs for the weapons in particular really caught my eyes, they almost seemed to be good enough to be used in video games in my opinion.
Sound: 7-8
I really like the OP and ED, and the music in between was well suited to each scene (e.g. the angsty flash backs, the fights, hints of romance scenes). No memorable OST if you're into that, though.
Characters: 7
Yu and Mika are officially the mains characters, but outside of their obsession with each other, there isn't much to be said outstandingly for them. Yu is the typical caring MC that looks out for his friends, hates injustice and draws people to him without really consciously doing it - so a typical shounen main character. Not bad, but nothing really amazing.
This anime did a good job with the female characters in my opinion, and I really liked Shinoa and Mitsu towards the end. Kimizaki also grew on me because I'm a sucker for tsundere boys (even though he's technically frost bitten through most of the show).
I think the show did a good job in getting you to feel for the characters. I got caught up in Yu's emotions just as easily as I was played into hating the Guren. These aren't flat characters whom you watch impassively. I was drawn in enough that I'm interested in reading the manga to see what happens to them.
Enjoyment/Overall 8
Like I said, I'm willing to go to the manga to continue on the plot which is a rarity for me since I'm willing to leave animes well enough alone at the ending they choose to cut off at.
The fights scenes and tension were good enough that I think this definitely fits into the shounen genre, and the small bits of comedy kept me happy enough to balance out the angst.
One thing that I particularly enjoyed that others might not is the chemistry between Mika and Yu. Not all people enjoy shounen-ai and while this isn't listed as such, it definitely carries an undercurrent of it and it would be amiss of me not to mention such. In that way it kind of appeals to shougo readers as well because there is a distinct element of wanting to 'fix' the other character, something that could only be done through friendship and love. While I definitely don't think this show is going to choose that route (the clear nihilistic line between vampires and humans this show plays to doesn't seem to call for an end other than the extinction of the other if you know what I mean) if you choose to come along for the ride, you're going to have to be prepared for how much Yu and Mika's relationship/brothership/friendship is vital to the plot.
Hope this helps anyone that was looking for the opinion of someone who enjoyed it. It may not be what you expected, but this is my honest take on the show. I'll be looking forward to their season 2 coming in October.
