I like that we have been able to build apps for our customers without having them paying us upfront, which would be impossible if they were not happy about their app being developed by someone else! The only thing i dislike at this point was when one client wanted another feature implemented into an existing application but there wasn't enough time so it had no chance getting done during my contract period as well (which ended after 4 months). In general everything has gone smoothly though - maybe because most people are very nice :).