I fell in love with Git because I could do frequent local commits that matched my workflow, only "publishing" them when it was appropriate, in the format I wanted. Git did this for me, Subversion didn't.

I know that concept does not have to be inherent to the D in DVCS. But for me that was the killer feature. It changed everything for me. The gain from being able to do that dwarfed all the costs of learning Git.