His serve is his only big weapon and if/when an opponent gets a read on it, he's very beatable. He also seems quite injury-prone which is worrying. He may sneak a slam like Roddick did but I think he'll have more of a Philippoussis type of career where he's always dangerous on fast courts but can't go the distance.
Well I don't think he is anywhere near in the same class as Roddick. Roddick IMO didn't really sneak out his slam. In retrospect yes, one say his slam was snuck out especially considering the SF with Nalbandian, but you have to remember all the hype and game he did possess back then. Despite having a rather strange game now, Roddick did pack a lot of power off the ground along with a bigger serve than Raonic arguably, and with adequate movement around the court. Raonic is not in the same league as young-Roddick was. I mean before he turned 21, Roddick had produced some very good results both at the slams and at smaller events as well. If I remember right, before Roddick turned 20, he won like 5 titles and made a final at a Master's event. Raonic is already 21, and time certainly isn't slowing down..