It's great. I want a second season. They're not kidding with the title, by the way. Tanya von Degurechaff is:
(a) an absolute monster who'll perpetrate massacres with an ugly psycho grin. She'll commit war crimes. She's a villain protagonist with no shame and no restraints.
(b) a little girl. I think she's about nine years old. She's horrifying because she's sort of adorable, if you're into twisted, vile, bloodstained abominations. (Every so often, very occasionally, she'll deliberately put on a kiddie voice and act her apparent age. Her reasons for doing so will be either hilarious or diabolical.)
(c) often very funny. She gets awesome reaction shots, since the animators can let rip with all kinds of over-the-top evil facial expressions. She also has a grudge against Being X (i.e. God), who she blames for everything and is planning to murder if she ever gets the chance. He reincarnated her into this body after she got murdered in her previous life, which was...
(d) the kind of Human Resources manager you want to push in front of a train. Well, guess what!
What makes the show work, I think, is the way it works on multiple levels. It's great if you're looking for Evil is Cool and a massive body count. It's fine to turn off your brain and munch the popcorn. (The show's also got a gift for black comedy.)
However it's also great if you're looking for something deeper than that. Tanya's been reincarnated on the German side in World War One. (Well, approximately. It's the early 1920s, all the names are changed and the military history's different, plus of course both sides have magic-users. However the maps, languages and cultural references are clearly Europe of that era.) The show's portraying war pretty realistically and you could easily start digging pretty deep into what these episodes are saying. The show could easily be interpreted as jet-black commentary on what people are capable of when we turn off our empathy. Tanya is both callous and clever in both her incarnations. She's very, very good at whatever she does. Her superiors approve and promote her. The world applauds her. Leaving broken victims wherever she goes is actually her job description.
Then, on top of that, there's possible character development for Tanya herself. We don't really want her to become sane, of course. Evil Tanya is the show's selling point. No matter how hard she tries to set herself up in a safe job far away from the front lines, we can see that deep down she's axe-crazy. (As a nine-year-old girl, she could have kept her head down and stayed out of danger for years.) However she's also extremely clever and has a 21st century historical perspective. Whatever job you give her, she'll be brilliant at it. She's also scary, obviously, but she's capable of being an excellent manager who can train and lead a top-class team.
Besides, Being X did all this to change Tanya. He wanted her to develop faith and become less callous. There's ambiguous evidence that this might be happening. By the end of the series, Tanya looks a lot like someone who cares about her adopted country and her subordinates. She'll skirt dangerously close to insubordination when she disagrees with her superiors' decisions, even though she once called that the worst possible crime and had been known to arrange the deaths of insubordinate men under her command even when they were right.
This is partly a cover. We know this. She'll quite often do things that make her look compassionate or even patriotic, just to look good to her superiors. However might it be possible that she's growing into her own mask? That becomes an interesting question in the last couple of episodes.
Oh, and there's also a short-form comedy spin-off called Youjo Shenki. They're just three-minute Flash animated throwaway that look like Blu-ray extras, but they were actually broadcast on TV. I quite liked them. They don't matter at all, but they made me laugh sometimes. The Tanya-Visha relationship can be funny, for instance. (Visha is Tanya's second-in-command and plays a deceptively important role in stopping the show from being too male and military. She thinks Tanya's nice. Admittedly there's some fear in there too, but Visha really does believe that Tanya's a splendid commander who cares about her troops. You can see the comedy potential, although it's much more understated in the main show.)
This show is awesome. I wouldn't go so far as to call it wall-to-wall non-stop cool, mind you. It's a bit too thoughtful and talky for that. It's interested in strategy and moral questions. Tanya spends a lot of time not really being evil, but merely a very, very good World War One commander. She does a good job and you can't argue with her courage. However the psycho faces are never far away, the sanity is questionable and she's always capable of doing something terrible. Her idea of fair warning in accordance with international law... oh dear. Give me more!
"Put a booby trap on that corpse."