We’ve been using Mercurial and Bitbucket at work for quite a while now. Things have been going pretty smoothly, and I don’t regret the choice of Hg over Git or TFS at all. Nor do I regret using Bitbucket as a back-end. They’ve had occasional outages, but probably no more than we’d have with Github or any other web-based service.
I had a bit of a problem pushing a really big changeset today though, so I decided to switch from HTTPS to SSH. It took about 20 minutes to set up, following these instructions. And I had to look here for some additional information on Pageant. I wish there had been a smoother, faster, way to get the whole thing set up, but it’s running smoothly now that I’ve got it all figured out.