After some initial battles (hint: knights in armour are no match for tanks) things quiet down a bit and the team gets to do some scouting and makes (friendly) contact with some civilians from the region. Through various adventures, they gain hangers-on in the form of an elf, a priestess of the god of death and a sorcerer apprentice -- things that push Itami's otaku buttons quite a bit... He gets to protect the civilians while demonstrating to the forces of the empire that it's best to be friends with the Japanese army!
It's an interesting mix of harem anime and a rather realistic depiction of what would happen if a modern military expedition would be met with swords. One part is kinda... cutesy, the other part is kinda bloody, which makes for a weird combination. But for me, Lt. Itami makes the series: he's a smart slacker with enough personality to make people work with him. I liked it a lot, though I could have done with depictions of battle that were a little less... gory.
The series ends right in the run-up to another plot, but I'm guessing the second series, which will start next season (this January), will pick right up.