Hidan no Aria
The premise is ridiculous: teenagers given guns and swords and some police rights, being educated to become mercenaries. I don't particularly like the lighthearted approach to weapons and fighting this story takes. However, if you can exercise some suspension of disbelief, Hidan no Aria can be a decently entertaining light watch.
Aria is your typical Kugimiya Rie tsundere: unreasonably violent (especially towards the male lead), skilled in battle but incompetent in matters of heart, short and flat-chested... you get the picture. A bitch you don't want anywhere near you, despite her occasionally flashing a cute side. She gets marginally more bearable towards the end. Well, personally, I like tsunderes, and while I prefer more balanced type, I have a high tolerance for violent bitches like her, as long as they do have a cute side that shows every once in a while.
Kinji, the male lead, is a total doormat in front of her, most of the time, but other than that, he's quite likeable. Plus, he does have some cool moments, thanks to his genetic ability, which greatly enhances his abilities and makes him a show-off in front of girls.
Out of the other characters, Riko is notable: she's totally the best girl in the show, and I doubt you'll find many who disagree with that. Her banter with Kinji is far more entertaining than any interaction he has with Aria or his childhood friend with yandere tendencies.
One thing that annoys me is that the story is populated by characters claiming descent from literary and historical character (such as Sherlock Holmes and Jeanne d'Arc), without actually sharing any important characteristics with said characters. All they have from those ancestors is some inherited (often supernatural) ability, which usually doesn't even correspond to the original character's abilities. There are some clan rivalries as well, but they're used in rather crude ways. It feels like the author isn't using even 10% of the idea's potential. A shame, really. I must admit, however, that I'm curious whose bloodline ability Kinji has inherited... a mystery left wholly unexplored in these first 3 arcs.
I haven't read the original novels, but it seems that this is a reasonably good adaptation. 3 first novels in 12 episodes. 4 eps for one novel is generally the ideal ratio for light novel adaptations, IMO. While the story has quite a lot of action, there is no feeling of rush. Unfortunately, that still doesn't mean this is anything special - it's hard to improve on mediocre, largely clichéd original material with no particular depth or intelligent plot. It's a light watch with little value besides the pure entertainment value.
As an action-heavy series, it's good that the animation is serviceable (as far as I can judge, I don't really pay attention unless something is really wrong or really well done). Pretty much what you can expect from J.C.Staff. Musics are the same, you barely notice them, they do their job to set the mood, that's all. The ED is pretty good, though. Edit: Actually, I gave it another listen, and some action scenes actually have pretty good musics. Maybe they're just played too quietly to get my attention... :/
Overall, I could recommend this for someone looking for a light action/harem story, who can stomach a violent tsundere character as a female lead. There is absolutely nothing original, deep or particularly intelligent, but I can't say I was bored watching it, either. 3/5 stars.