Lately I have been switching to using git. I have always been disappointed by the poor merge tracking support in Subversion. Even the 1.5x series has uninspiring merge tracking support. Also my new employer uses both git and Subversion, so this gives me a good incentive and opportunity to finally learn git.
Subversion has flaws and limitations, but it's a lot better than CVS and it's cheap. The low price doesn't reflect low quality or lack of support. Subversion does not do distributed version control very well and merging is frustrating; although, a few simple third-party tools make it tolerable. It is also difficult to automatically generate reports that graph changes. The problem is that all the commercial offerings are very expensive. ClearCase is expensive to buy and very difficult to maintain. It is complex. Perforce is probably better, but it is also expensive. It's hard to beat free! I have also been tempted by Git, which I suspect is better than Subversion, but I have more time and experience invested in Subversion.