Pros
Great people, pay and benefits are good, and there seem to be ample opportunities to move around within the company so you aren't locked-in to a specific job/role. The main campus is nice enough, and the company is heavily involved in the community. Many of the managers I know appear to take a genuine interest in their employees.
Cons
Long hours, and very stressful at times. As with many companies, employees are being asked to "do more with less". A lot of work is now being outsourced, though it has led to only a small number of layoffs so far. I've heard the IT area characterized as a "sweat shop", though I think this varies greatly depending on the area in which you work. In my opinion, they do a very poor job prioritizing the project portfolio and everything seems to be "equally important" which leads to way too many projects going on at the same time, everyone competing for constrained resources, etc. For the past 2 years, HCA has made Computerworld's "Best Places to Work in IT". Not sure how. Even with these cons, I'm satisfied overall with my job at HCA. Still, I doubt I'll be here a year from now.