Big deal. They brush off your skin. Better than nothing. Use whatever you can until you have access to a power rack so that you can do your squats and deadlifts using a bar and weight plates.
I don't find Powerblocks much blockier than regular dumbells. The big disadvantage to Powerblocks aren't the fact that they are blocky. The big disadvantage is that when you are doing movements like the chest press, you can't really bang the weights together real hard. And, of course, you can't drop the weights on the ground real hard either when you are lifting heavy. The Powerblocks aren't intended to take that abuse. I don't like Powerblocks for that reason.