Fabrizio Giudici's Blog: Switched to Mercurial
"asynchronous mode support. This might not be the most important thing, but I love the fact that Mercurial commits locally, so you can work without being connected. You should know that I love to be disconnected, if possible, and other times I can't be connected if I'm traveling (and with the incoming August I'm going to move for a month to the countryside). The requirement of synchronous operations by a centralized SCM such as Subversion is really annoying if you like the "commit often" approach, like me: if you are not connected, either you can't work, or you are forced to change commit style, which is no good. If you have a mobile connection, which is often slow and intermittent, "commit often" works but you loose lots of time while waiting for commits to be completed. With Mercurial, commits are immediate, so you can work as usual. Then, a few times per day, you do a "push" to synchronize the primary repository - this might take a few time, but you can run it while you're doing something else (another job, you're eating or having a bath)."