The STORY of Battle Girls reminded me greatly of InuYasha, but I am a big enough history buff that I didn't care. However, do be warned - this is NOT a historical account. After all, a girl is going into the past so things are going to change. I was originally irked that things that were suppose to occur didn't (in fact the OPPOSITE happened), but if you can get past that and focus on the fact it's not trying to be historically accurate, it's a cute anime.
I didn't particularly care for the ANIMATION. I thought that everyone's breasts just seemed so... ridiculous. Especially Nobunaga's... it was completely disproportionate! And of course everyone wore as minimal clothing as possible. It wasn't only their breast size, however. (Keep in mind that this anime is trying to appeal to many - and there really wasn't that much fanservice). This anime is very cartoon-y and I generally don't like that look.
I actually rather liked the OP and the Ending and was very impressed with all of the seiyuu's work in this. I especially loved Nobunaga's voice. I thought it captured who she was (he was?) perfectly, and Hide's voice was sweet as well, without turning her into the typical, bubbly cliche.
If you can take them out of the historical context, then the CHARACTERS of this anime are very fun! I didn't want to rate them higher than a 7, however, because they are kind of "cheating" considering almost all of them were already historical characters. They sort of had an upper in this. However, their take on Hideyoshi, Akerin and Nobunaga was absolutely fascinating and I loved watching all of the character interactions.
OVERALL, I would recommend this anime. There is a bit of filler that I definitely could have done without, but for the most part, it follows a central plot of a journey and has a sweet character development. My favorite part was when Hideyoshi was about to return with Date and she was handed her cell phone. She said, "I forgot about this!" THAT is character development at it's finest!