I like Corbet's inclusion of other perspectives than the "horse race" perspective. It can be fun and exciting to imagine open source projects as horses at a race, or as combatants in an arena, but when I'm not thinking in those terms, I realize that bzr is working well for me.
I use bzr to interact with projects that use it. It was easy enough to install and to learn the basic (getting a copy, updating to the latest version, submitting an occasional patch). It's efficient enough. It has not yet stunned me with an incomprehensible and intimidating error message. I'm basically satisfied with it.
Likewise I'm pretty satisfied with mercurial, which I also use only for occasional interaction with projects that use it.
Now git and darcs, I've used -- or tried to use -- extensively in many of my own projects and for my employers, and with both git and darcs I have a love/hate relationship. It's complicated.
Then there are the projects that still use svn or cvs. I find it mildly annoying to try to interact with those projects using those old tools.