LOL at the notion that Marin is the "German Messi".

He is fast and has a nice shot, but he can only attack (he actually hustles on D, but he is the worst tackling midfielder of the entire NT) and is too easily intimidated by physical defenders. In comparison, Özil's technique is three classes better, Podolski scores more goals, Götze has 40 points more soccer IQ, and Müller's ability to play off the ball is much better. But still, Marin still has upside, and I think that the change of scenery could benefit him.
Edit: Marin reminds me a bit of Marco Reich (remember that guy?), but in contrast to Reich, Marin at least is a humble, down to earth guy.