They're great fish. I have 3 juveniles, and they are constantly schooling together. I thought they would be more independent like my Rams or other cichlids but they seem to really like their own company. Extremely mellow fish, but they do get scared easily.
Also, I have found that they really like eating algae. In fact, mine do not really like any of the blood worms or other meaty foods I feed, they just pick around at the rocks all day. I once put a piece of bog wood completely covered in thick algae in my tank and my keyholes ate all of it in one day!
I also hear they mature very slowly, so if you are looking to get a male/female pair, you should buy 4-5 now because it is hard to find adults in stores.