The film does everything the show does - quite literally, in fact, as the set-up is the exact same premise, boiling down to about an hour and a half of tank battles and half an hour of emotional fluff. This may seem lazy to some, but if you were sitting down to this show expecting something other than the thinnest pretense to feature lots of explosions and character service I don't know what you were watching to begin with.
As far as providing character service and explosions goes, the movie does a decent job with both. All the favorites return and characters such as Katyusha and Anchovy get a surprising (and welcome) amount of screen time, but given the need to cram so many characters into two hours there are many others who are reduced to a few soundbites. Things like Yukari's sneaking missions or... whatever the other characters did are notably absent. The opposition, unlike the teams in the series, isn't given any sort of obvious characterization and functions only as another obstacle for the underdogs to overcome. Belying the prodigious amount of art featuring her the head of the new opposing team is relatively nondescript beyond her character design - other than being a loli who's good at doing tank stuff and likes a certain stuffed bear there's little else to say about her and she gets relatively few scenes.
The battle scenes - making up the bulk of the film - are good-looking and well-executed. There are some new tanks introduced as well (one of which causes a lot of big, nice-looking explosions), although unlike the show we aren't given much background information about them.
Beyond the characters and the battles there's relatively little to say about the movie - the focus of the remaining half hour is largely the characters feeling sad and, unlike the show, the planning process for the battle is relatively short. There's some bonding between Miho and her sister but here too the film treads lightly and mostly functions as a 'feel good' bookend to the events of the show. The battle between schools ends somewhat abruptly and the aftermath is some brief scenes set to music while the credits roll - but then, given the thin excuse for a plot, were you expecting anything else?
