Well, let's be honest: Girls driving tanks, everyone is here for the plot, and you are not quite wrong, actually, but there is so much more when you watch the anime.
First of all: This IS NOT Youjo Senki, this girls are not in a war, they are involved in a sport called "Panzerfharen" and it is a martial art. They are fighting for the achievement of the World Cup. The anime is full of cultural references of European Battles since the beginning of the Otoman Empire till WWII, the teams are divided in High Schools for girls only, and each High School represent a country: as far as i could see, those countries were: Japan, Germany, Italy, UK and USSR. The battles are so realistic by the way.
Now, the bad part: The animation is so poor: most of the girls have the same body shape and face shape only changing the color of eyes and hair style. The only different girl is the Pravda Commander Katyusha (By the way: she appears at the first time dropping out of a Katyusha rocket launcher, introducing herself as Katyusha and singing the war song: Katyusha hehe). The jokes are so repetitive and the characters have no kind of evolution, and new teams appear in the chapter 10 without knowing anything about this girls whom were in the same high school all the time.
Conclusion: Good anime, not great, the plot is different and curious but nothing more
7/10