Anytime I visit the doctor, they always have Epic up on the computer. Granted, I know I'm living in the city where it's made, but it's used across the country. I even had a friend who moved out West and planned on just finding a random job, and it ended up being Epic to help install the software at health clinics in Washington.
I don't know their full stack of offerings, but I used some of their treatment billing software when I worked at a health care insurance company during my college summer vacation. It worked just fine, but certainly had an old software feel to it. I don't know if they offer any cloud offerings right now (their website sure doesn't make me think they do), but if they do I find it hard to imagine it's anywhere near as powerful as something that Salesforce could offer right out of the gate. I work with Salesforce every day where I work now and I have to admit it's very well done, although they certainly fall short in some areas.
I don't particularly care about Salesforce or Epic so long as my data is safe, but I'm interested to see how it plays out since it impacts my community.