First off, windows integration is especially beautiful. You don’t need an extra shell, you don’t need Cygwin, you don’t need OpenSSH. It’s just a great experience in Windows. I’m also using TortoiseHg. TortoiseHg seems to be a better experience than TortoiseGit and they’ve paid closer attention to the collective dismissal of windows on pressing OK, an annoyance to me with TG.
Furthermore, UTF-16 files seem to be supported out of the box (probably because Hg’s written in Python). A project that I frustratingly tried to commit to a Git repo was a breeze with Mercurial due to the UTF-16 support. The way that Visual Studio saves files, you can’t be certain that UTF-16 won’t be the file format, but that is a non-issue for Mercurial, which eats ’em up with out a blink.
Lastly, support for massive code bases is a big win at my company where our source repo is upwards of multiple Gigs. Git’s premise that the Linux Kernel source is “huge” is utterly laughable. Mercurial swallowed up our code quickly and didn’t have any issues diffing changes and I didn’t have to go figure out creating sub-repositories to get better performance. This singular feature is HUGE to me.