I'm pretty sure he's talking from the user's perspective, not design/implementation.

Eh, I am coming from the perspective of a user, not a VCS developer. I find git repositories way easier to navigate, let alone perform complex operations on, because how they work couldn't make more sense to me.

From a user's perspective, Hg is so limited I consider it basically unusable.

I seem to get my stuff done in either. What's missing for you in hg?

Being an active user of both git and hg, I also can't think of any features I make extensive use of in git (rebase, feature branches, etc) that I can't get with hg. My workflows in both are pretty much the same, just a saner interface on the hg side. If anything, git doesn't have revsets, a really powerful query language you can use to sift through your history - see http://www.selenic.com/hg/help/revsets

rebase -i and add --patch were the dealbreakers

Also I have yet to see a hg tutorial that didn't at some point recommend making a second clone of the repo in order to do something complicated.

As someone once commented, git is a great library for building a VCS system. Great design.

The tooling around it? Not so much. http://stevelosh.com/blog/2013/04/git-koans/

The default tooling is either your cup of tea, or it isn't. There is great 3rd party tooling available if your tastes are different though, such as where Github and I assume Bitbucket are moving. I think those are probably the future of git (and/or mercurial) use for non-technical users.

Probably mercury poisoning. It will make you as mad as a hatter. Symptoms include inability to rebase branches or rewrite history, choking on large repos, inability to do more than two-way merges, and clumsy handling of branches. Clean cup, move down, I guess.