Kiln gets you a pretty cool (if I do say so myself) code review system, an all-new web interface for managing your code and repositories, tight integration with FogBugz, and support from Fog Creek. If you don't need those things, then by all means, use the open source version.

There's a free trial of the hosted version that you can sign up for at http://www.kilnhg.com/. Also, Kiln and FogBugz are both free for Students and Startups (2 users or less). Give it a shot and let us know what you think.

As a kiln user, I'll back up Jason's statements here. Working with it day-to-day, it's not really any different from using the open source version of hg, but the web UI and code reviews are pretty damn cool.

Kiln also takes care of all configuration/setup for you...and the On Demand version gets you regular off-site backups, secure data center hosting, all that good stuff.