The best cross-platform DVCS. It Just Works™ and is intuitive especially if you come from SVN. It's safe out of the box as it doesn't let you accidentally corrupt your history, but once you're more comfortable with it, you can activate plug-ins that will let you modify the history (and in the repository). I write "activate" since a lot of them are already part of the installation.
Our users have written 1 comments and reviews about Mercurial SCM, and it has gotten 121 likes