I've heard the same, but mine climbs like crazy. I've even seen it climb on glass (once). I tried to take a photo but my camera batteries were dead!
It eats algae like crazy, and has successfully cleaned all hair algae that I had in my tank (slowly). That's right- i have zero hair algae in my tank now. The only downside is that it's gotten stuck in between some rocks a few times, and I've saved it. It sounds crazy, but it's almost like it has learned from these experiences and avoids hanging around the places that it was stuck before.
Another good point- I have a reef lobster, a slipper lobster, and a brittle star that have never attacked it to my knowledge.
Great reef addition, in my opinion. Cool little animal.