I've been using Subversion for about a month now and I must say after suffering through CVS for years its lovely. The tipping point for me was when I could install it from the stable branch of fink on OS X.
It does just what its designed to do, its a replacement for CVS. After wrapping my head around the few architectural differences I'm completely comfortable with it. Its fixed the stupid CVS problems. Files and directories can be renamed while preserving history. Branching is simpler. You can turn off $Revison$ munging on a per-file basis. The documentation is much better, each command has its own help page (svn help ) and the online SVN book is quite nice.
My advice for CVS users switching to SVN: Read Appendix A of the SVN book first. This lays out the major differences between Subversion and CVS. Also, jump directly to version 1.1.1 and use the new FSFS repository type. A lot of the problems you might have heard about SVN stem from the old Berkeley DB format.
What's missing? XEmacs vc-mode support. A few little interface nits (svn mkdir -p, svn tag). Its still a bit slower than CVS.
I'm moving my CPAN modules off CVS and onto my SVN repository as I work on them.