[Joel on Software](http://www.joelonsoftware.com/items/2010/03/17.html) has this to say about Mercurial:

In Subversion, you might think, “bring my version up to date with the main version” or “go back to the previous version.”

In Mercurial, you think, “get me Jacob’s change set” or “let’s just forget that change set.”

Plus, he wrote a [Mercurial Tutorial](http://hginit.com/).