I have a singapore angel, i think i have a shot of him in my gallery somewhere.
He is about 2 inches long and its doing well in my tank. He is generally peaceful, do does not bother my maroon clown or bluedot toby, but he will act territorial towards my 2 fairy wrasses (he has a little nook that he'll chase everything out of.) I did try putting a copperband butterfly in my tank a while ago and good god the singapore angel would not leave the poor thing alone no matter where it went, which is odd considering everything I'd read said singapore angels were very peaceful, but then again it is an angel and it does kinda have a similar body shape to the butterfly.
I had no trouble getting it to eat anything I offer it; spectrum pellets, mysis shrimp, frozen krill, and occasionally some sponge-rich angel food.
Its a relitivly active fish but its not all over the tank all the time like the wrasses, I guess you could call his activity a sort of 'patrol' haha.
All in all, I like him, I dont have coral but I have read/heard they would be ok, and Ive even read a few places that they are more likely to be ok with another angel in the tank (one of the few angels that are ok with multiple angels, most likely due to the singapore angel being smaller than other large angels, only gets about 7-8" max... but I have not actually talked to anyone who had any success or lack thereof housing a singapore angel with another angel so dont take my word for it