Just tried him on the PBE, definitely not what I was expecting for an "assassin" character. I'm really not sure what to do with him because his damage just seems to be lacking with his low survivability. Feels like his is supposed to be an assassin but doesn't quite fit so you build him bruiser. I did have terrible shadow use though so maybe once I nail that down he will get much better.
Though that is another thing I have to complain about. For a champ based around his shadow, it has a fairly long cooldown.