So far as corals go, I haven't heard of many problems. They will, however, eat any and all tubeworms, shrimp, etc. Be aware that these guys are pretty poor shippers, so if you're going to get some, make sure your lfs quarantines them. They also do best in a school of 3 or more, 6 would be preferable. Of course, it all depends on the size of your tank as to how many to get.
-Jason