[gecko]

Having taught people both systems, I will assert, based on my personal experience, that while some developers can certainly pick up Git relatively painlessly, picking up Mercurial objectively requires less time, and leaves users less likely to get into a state that they are unsure how to exit. This is purely based on my own personal experience, and I have not scientifically codified the learning time in double-blind testing or whatnot, but it's a data point based on more than just my own personal meandering attempt to learn the two tools.

EDIT: I am not making a value judgment here. It's harder to learn to fly a plane than drive a car, but that hardly makes the car better than the plane or vice-versa. It's just a recognition that their learning curves aren't identical.

[Xurinos]

Having introduced git to a few groups (and some hg), I found that the main thing that makes hg easier to learn is that hg mimics some of the same names of commands as cvs/svn. However, once they understand what is going on in git, the aha moments start to show up, and the really complicated stuff becomes easy.