It's been highly praised, but I have slight reservations. I don't know if I'd recommend it. It's a Battle Royale, where schoolgirls fight each other in goofy giant robots for the right to be the world's last mage. It's ambitious, flamboyantly animated and has some pretty extreme revelations, but...
(a) I don't think the fights work. The animators have gone to town so much that I can't tell which almost indistinguishable giant robot is which. (They're all super-deformed, i.e. as wide as they are tall, with tiny limbs and big heads.) Furthermore, the action's often so explosive that I couldn't tell what I was looking at. When some legs got chopped off in ep.13, I didn't realise until it got mentioned in dialogue. "You lost your legs? Oh, right. Should I have noticed?" Result: it's often just a big action mess. Wheeee. It looks great, but it's not so good at being connected to the characters.
(b) it's a battle royale with a passing resemblance to Fate/stay night. These tend to be a bit pointless, e.g. Fate/stay night. Admittedly this pointlessness is one of the show's targets and it's got a fair amount to say about magic and the people who set up and fight in these contests, but it still feels arbitrary. Girls fight! Why? Uh, because they want to. Gee.
That said, though, there's a lot to like here.
I like Mangetsu and Shingetsu, which is good since they're the main characters. Ep.11 is actually good, thanks to them. It's showing some pretty crazy ideas and strong emotions. I like the dissection of "I have nothing". I like the subversion of the set-in-stone "oishiiii!!" anime reaction to all food, ever, unless the joke is that it's toxic and inedible. Mangetsu herself is very engaging and the token Ordinary Girl in a cast of intense mage-wannabes.
I love Anna, who's a magnificent psycho. Look at those faces. Wow.
I disliked Suishou a lot, but I'm supposed to. She's a smug, purring snake and ultimately a hate figure.
Nene-nee is also cool.
It's a show of two halves, really. The first half, with more Anna, is splendidly entertaining. The second half is colder and more idea-driven. Mangetsu and Shingetsu provide a strong emotional story, but I found it harder to get involved. I found the baddie a bit off-putting and stopped caring as much. I'd never cared much about the whole battle tournament thing.
The show's enormously proud of its battles, but the first battle I didn't find boring was in ep.4. I liked the real world stuff, though. The characters are well written. I like what the show's saying. It successfully walks a difficult tightrope in the final episode. I'd recommend eps.6-7 for Anna, but I wasn't as keen on this show as some other reviewers are.