One thing however is really amazing: it contains a built-in web user interface! Just while being inside the repository type "hg serve" and browse to http://localhost:8000. And there's more to it. "hg serve" can serve as a real server!
There's one thing worth mentioning. If you'd like to use it for hosting a repository there's one thing you have to add to .hgrc (or Mercurial.ini in case you're working in Windows) to make it work:
allow_push = *
push_ssl = false
Otherwise while trying to push the changes you'll get a message saying something SSL and stuff.
And like I said - Mercurial is great - go check it out!