Roy kicks ***. He's not a coverage safety, so the sooner people get that out of their head, the better. He's not as big a liability as people make him seem either. Roy is one of the most dominant forces in the league, when used correctly. If you can get him near the LOS, he makes things happen. Fumbles, tackles for loss, sacks, that is what Roy does.
As for your comparison to Polamalu.
ee: I pee on it.
Roy is better than Polamalu, he just doesn't have interesting hair. Or any hair, for that matter.