Why bzr and launchpad? Launchpad is open source.
A few months ago, I mentioned on HN that I've switched to bzr again... after having troubles with it a few years ago. Then someone asked me to report back after a month or so to say how I went.
In short, bzr is going fine for me. I've had none of the problems I had before. I think in large part because they've settled on stable releases, and development releases. So they are concentrating on making a stable release, at the same time continuing their great pace of development on their development releases. Also, the file format seems to have stabalised... and just lots of polish generally I guess.
All new projects I've been using bzr. As well a few open source projects of mine I've released using bzr+launchpad. Also there are a couple of launchpad bzr using open source projects I've been using.
Finally I've used it with a couple of subversion projects... which work really well. I just create a bzr branch... which downloads the whole history locally. Then when I commit, it commits to the svn branch. However, I can easily branch with bzr and commit to that branch, before merging back into svn. Haven't had any trouble doing it that way.
Anyway... there's my bzr experience. No issues this time around. Kind of boring, like how a vcs should be.