Shingeki No kyojin: Kuinaki Sentaku is the story of Levi and his friends Isabel
and Farlan live in the underground district where the most poor of the population live and to even get to the surface you have to pay a toll to use the stairs. Levi is a thug that dreams of a better life and escaping to the surface.
The story of how Levi got to be in the Survey Corps is interesting enough and it seems to be executed well. Of course it is a prequel so it faces the typical prequel problems, the fact that we know that he survives and that everyone else who doesn't appear in the original show probably doesn't make it and so on. But that aside they are successful in that the show really feels like AOT and if you liked the story of AOT you will like the story here.
The animation is great, the action is super awesome and smooth and everything else gets the job done. Actually I was slightly disappointed that it wasn't better than the original show as you would assume that they have a humongous budget this time around but to be fair the original show looked pretty damn good already.
Overall I enjoyed the first episode of the new ova series and this is easy to recommend. Did you like Attack on titan? Yes - you will love the story of Levi and it will probably keep you satisfied until the next season. No - you won't like this and probably can skip this without any problems.