Let's start with this: I am a HUGE Tales game fan. Tales of Vesperia was my second Tales game, and I must say it's my favorite. Although he does break the laws, the main character Yuri is much like a vigilante. He fights for the right reasons. In contrast, they show Flynn off as the "goody-two-shoes" who believes in order to change the military and government you must work up the ranks. Both of them show that by whatever means you can, in fact, change things if you try.
The entire game is based off of fighting, and some characters even get killed. There's not much blood; only in one or two cutscenes. Overall it's a great 4-player game that your teen and his/her friends will enjoy for years to come.