He's got the skill set with a combo of speed, leaping ability and very decent hands, but his frame is still a concern, in the Seattle "O" he's gonna get sent over the middle, where he will be hit by NFL DB's who are men, not by some 5"10" 170 college boys who will never see the inside of an NFL locker room. He will also be asked to block for that run-predominant offense and IMHO again his frame is not set up, right now, to handle that effectively.
Like Roberson in BB, I'm glad he was drafted high enough to make a financial difference in his life. But his long term success in the League, is still an open question.