Mercurial vs Subversion

Mercurial is yet another version control system. According to its' book, here are the main differences to Subversion:

• Mercurial is distributed, i. e. each Mercurial client has his own complete copy of repository, including whole history. That's the main difference to Subversion, which is client-server, so other differences can be considered as side-effects of this.
• Merge is much better in Mercurial, which makes it easier to use branches (always a big pain with Subversion). This is really required, because it's the main mechanism of sharing code between developers.
• Performance - Mercurial is in general somewhat faster.
• Space - Mercurial is more efficient when consuming disk space.
• 3rd-party integration - Subversion has more integration means, at least now.
• Locks - Subversion provides locking mechanism, which is suitable for working with large binary files. Mercurial is not that efficient in this respect, also due to its distributed nature.
• Import/Export - Mercurial is able to import and export data from Subversion, CVS, git and others. It makes it easier to migrate to.

A simple way to start with Mercurial (at least for Windows users) is to download TortoiseHg installer for Windows (all included).

Also, Bazaar should be considered as an alternative (here is a good article comparing and explaining those). Yes, Mercurial appears to be much simpler in install and more than 2 times faster than Bazaar for nearly all operations.