One of the hardest things a business can do is provide great service. For software companies moving into providing services in the Cloud, this is a big paradigm shift. It's not good enough any more to just throw out a new version of your product a couple of times a year. Now you have to engage in continuous improvement and engagement with your customers. That's not easy, especially if you haven't ever provided Services like this before.
Seth Godin has another great post on some of the balance required to provide great services. Read it here.
On a separate point, I don't really like the term SaaS (Software as a Service) for the simple reason that it should be less about the software / technology and more about the services. I would like to see this acronym fade over time and get replaced simply with Services. That's what it's really all about for customers.