I watched an interesting video from Google IO 2009: http://code.google.com/events/io/sessions/DoYouBelieveUsers.html. They where talking in general on how to get a higher usability (addressed to an engineering audience (read: no Human Computer Interaction designers)). They had a graph where they placed different programs where the left of the graph where users with little experience and to the right users with extensive experience. I cut and pasted the Git vs. Mercurial comparison:
In my opinion usability is everything! This means that I will give Mercurial a go and see if that fits my needs. If it doesn't I will perhaps give Git a go.