Story (4/10)
This is one of the main weak points of the anime, the lack of story. I wouldn't say that there is no plot, but is too ambiguous and bad connected. Most of the things are not explained at all, so you'll have to deal with it and imagine things on your own or checking them in Wiki's. I give it a 4 just because at least they didn't invented a complex story and if you take it as a some kind of slice of life it isn't so bad.
Art (10/10)
I can only thing of the art as superb. It's difficult to review it just because everything in this regard is just perfect. Character design, animation, light, color... all of them are of the highest level. This anime uses a lot of CG, even on the characters, but in a such a good way that enhances the animation without making the characters look bad. I specially liked how the planes were animated. I love WWII planes (more than ships, I'm sorry) and I want to marry the people that animated them for this anime.
Sound (10/10)
Same goes here. I don't usually like the opening and ending songs of animes. I know there are people that like them but I don't. But in this case the opening was, in my opinion, even good, which is a lot to say coming from me. Apart from that the voice acting is really impressive and the sound of the battles just amazing. I would recommend to see this anime with a nice sound system (or good headphones) so you can fully enjoy the battles.
Characters (5/10)
There are a lot of characters. Really, a lot. I find this both good and bad. On the one hand you won't get bored of the same characters all the time, mainly because they are to plain, but on the other hand is impossible, at least for me, to know all of them.There were times when they were talking about somebody and I didn't know who. In any case there is almost no development on the personalities, and I give them a 5 because most of them are funny and different.
Enjoyment (9/10)
I really enjoy seeing this anime. It is very funny with a lot of jokes, a lot of stupid characters... It made me laugh plenty of times. The battles are really well made and I also enjoyed them. There is even a bit (or more than a bit, but nothing hardcore) of yuri which is always well received in my case.
Summary
My overall mark is 8/10. The lack of plot and the simplicity of the characters contrast with the outstanding art and sound. From a technical point of view this anime is just amazing but it won't change your life in the slightest. In any case is funny so if you have some free time it's a nice idea to give it a try.
