For some people. Back when I only knew how to use subversion, I tried out both git and mercurial, and found mercurial confusing while git clicked immediately.

Unfortunately it's been long enough I don't remember details why, just that it was something with how it handled branches.

Mercurial has both "real" branches (history is kept so you can always tell what revisions were in what branch) as well as git "branch is just a pointer tag"

So really you can choose whatever suits your needs.

Personally the things I love about mercurial are:

    more consistent commandline (that's the simple part others bring up)
    revsets (awesome query language for revisions, there's also filesets, but I don't use that as much)
    absorb  (I think someone added a git extension that does something similar a few months ago)
    fa --deleted 
    grep --all  
    phases ♥