The story of the OVA is relatively compact and only a small part of Levi's life is shown, this being how Levi met one of his friends, how Levi ended up accepting a big commission and how Levi ended up joining the survey corps. The important characters are Erwin, Levi and two of Levi's friends.
The animation is good and is in the same style as the main anime and of similar quality. The voice acting is the same as in the main anime but some of the music choices were a bit odd.
Overall this OVA is definitely worth watching since it's both simply high quality with an interesting story and it adds to the main storyline by explaining part of Levi's backstory.
