Considering the number of fairly serious outages and security breaches that have occurred with these cloud based systems, I believe that people could be forgiven for thinking that it's probably not quite such a good deal as the sales people make out.
My own experience would make me very reluctant to go down that route at any price. I'm sure that there are companies that do provide a great service at an excellent price; but I've yet to work with one that I would trust.