The question which version control system is "the best", is often the base for endless discussions. I'm quite pragmatic in this regard: I've used Rational Clearcase during the last 9 years and worked with CVS and Subversion during the last 4 years. From my experience the acceptance of a version control system depends a lot on how it matches to the software development workflow of a company/community.
Personally I prefer the straight forward approach of Subversion over the (technically) powerful Clearcase. Still Subversion is cumbersome when working with temporary development branches and I was curious when I heard about the concepts used in Git. After reading about Git I thought that it unites the benefits of Clearcase and Subversion without introducing any drawbacks.
At Openismus I got the chance to work with Git on a real project. The first impression was ambivalent: On one hand Git is extremely powerful, fast and does not limit the developer how to work with branches or doing merges. On the other hand the learning curve is higher than expected and it requires a different mind set in comparison to centralized version control systems. Because of the huge amount of new possibilities a ruleset for projects using git is highly recommended. Git reminds me to C++: You can do wonderful things with it in a clever way, but it's very easy to shoot oneself in the foot.
I still need to learn a lot about Git, but after a few weeks of working with it I already prefer it over Subversion a lot. More and more projects switch to Git, so this does seem to be a common experience.