There's a plethora of SCM software out there. Ever since the subversion guys tried to supplant CVS (because quite frankly, CVS needed fixing), SCMs have become the new mail client/editor, i.e. "software you must have written yourself at some point".
Then Tom Lord brought arch onto the scene, and introduced the revolutionary idea that SCMs should not follow a centralized, but a distributed model (apologies if my chronology is wrong here, this is how I experienced the development). Except for a few arch spin-offs, not much happened for a while.
A few years later, though, suddenly distributed SCMs were the thing to do. Since then we've seen monotone, git, bazaar, mercurial and svk rise in popularity.
Since a distributed SCM was what I needed, and wanted since arch, I tried them all at some point... and stuck with monotone.
Now I should mention that when I decided to stick with monotone, git and mercurial weren't around yet. Compared to the others, though, monotone shines on the following points:
not trashing my repository
clear development vision/design
friendly developer community
upgrade-path from earlier versions
not trashing my repository (yes, it's important)
I primarily reviewed git and mercurial because they could, in theory, improve upon monotone. What put me off the former is that it's really a fairly loose collection of tools, written in multiple languages, and without any coherence between them.
Mercurial on the other hand looks fairly cleanly designed - but it's slower than monotone, and doesn't add anything I need.
In the end, by these criteria, monotone is simply the best SCM I've tried so far. That's not to say it's entirely free of warts, of course, but they're easily dealt with.
All that's left to say is this: try it for yourself!
I've been hunting around for a decent database abstraction layer for node.js for a while, and none of the likely candidates met my needs: they were either unmaintained, had horrible code quality, or I ran into too many bugs.
This project seems to take a more minimalist approach and I managed to dig into the code base quickly to make some minor modification. The owner/maintainer responded immediately, gave concise and useful feedback, and when my modifications matched his standards he merged them without fuss.
Between the code quality, the experiences with using it, and the responsiveness of the community, this could become a very meaningful project very quickly.