These points are taken directly from the Subversion project web site.
Subversion is meant to be a better CVS, so it has most of CVS's features. Generally, Subversion's interface to a particular feature is similar to CVS's, except where there's a compelling reason to do otherwise.
Lack of these features is one of the most common complaints against CVS. Subversion versions not only file contents and file existence, but also directories, copies, and renames. It also allows arbitrary metadata ("properties") to be versioned along with any file or directory, and provides a mechanism for versioning the `execute' permission flag on files.
Some links to why VSS might not be the best choice of version control system.
I currently manage a group of about 20 developers for a Fortune 500 company. We used CVS from January of 2001 until May of 2004 when we converted all of our repositories over to Subversion.
The advantages we received from Subversion are immense. Before our conversion to CVS from VSS, we had two full time employees managing our production builds. Upon conversion to CVS we cut that resource count down to one. This resource handled all branching and merging activities, reporting activities, and manipulation of the CVS repository to move files while retaining history. The CVS branching and merging was just too cryptic (and took too long) for anyone to want to learn it. We had two CVS "experts" in house which included me and one of my direct reports. We were constantly called in to resolve issues. I myself spent a ton of time managing the support of the CVS repositories.
Just wanted to drop you a quick note about how incredibly cool Subversion is... I think sometimes getting bogged down in the bug fixing, feature requests and roadmaps discussions that you can lose focus of what an incredibly cool tool Subversion is...
My background, we just recently converted over from a CVS repository. I thought I would share with you some of my experiences as a way of saying thank you:
I am a big history freak. One thing that always sucked about CVS was that it made refactoring so hard to do. By and large I was able to bully people into telling me when they want to move something around so I could manually copy the RCS file, manually delete out the tags that no longer applied to the new location, etc (eugh...what a pain). But all too frequently, joeblow would "move" something by cvs rm-ing it and cvs-adding it, thereby creating the impression that the five year old foo.java file was created yesterday in its entirety by joeblow. Drove me nuts. Just yesterday one of our devs took about four hours and did a "marketing" refactor, changing a bunch of our classes to match the terminology we actually use when talking about things. I pull up the newly renamed file...there it is with all of its history intact. It brings a tear to my eye. :-)
Do you need another version control system which is more scalable than Visual Source Safe? Are you a CVS user who finds the lack of directory versioning a difficulty? Are you paying too much for your current version control system? Do you not use a version control system right now?
If you answered yes to any of the above you need to look at the Subversion version control system.
The original design goal of Subversion was for it to be a compelling replacement for CVS. However, it is also an excellent version control system in its own right.