&gt; Lest we forget, Mercurial was offered as the other solution to the Bitkeeper problem, as mpm was a kernel hacker at the time. It got a usable UI at version 0.1, two weeks after the git announcement.<p>I remember using Mercurial very early on in its lifetime, during my first internship at IBM, because Xen used it.<p>Mercurial also ran on Windows far, far earlier than Git did.  A few projects (notably Mozilla) selected Mercurial for that reason, because they had developers on Windows.<p>Unfortunately, Mercurial took longer to develop some of its infrastructure, such as a repository structure optimized for performance, fast branches without making a separate working directory for each, and history editing capabilities.  Today, as far as I know, Mercurial does have all of those things (some through plugins).<p>&gt; Some git users relied on cogito for another year or so, as simple things like `git-commit` still had to be manually handcrafted out of `git-commit-tree`.<p>Many people (myself included) also used cogito as a crutch for a while longer, until really internalizing the value of the git index, because cogito defaulted to bypassing the index.  I originally saw the index as an obstacle to the commit model I&#x27;d gotten used to from subversion.  Today, I find it a critical part of git&#x27;s culture of making small commits with one logical change each.