I'm not going to lie to you; mercenary.vim may very well be the worst Mercurial wrapper of all time.
Here are some screenshots showing off some the mercenary's dirty work:
:HGblame will annotate the current file with the blame.
:HGdiff {rev} will diff the current file against the specified revision.
:HGshow {rev} will show the commit message and diff for the specified
revision.
:HGcat {rev} {path} will show the specified file at the specified revision.
If you don't have a preferred installation method, I recommend installing vundle and adding
Bundle 'phleet/vim-mercenary'
to your .vimrc then running :BundleInstall.
If you prefer pathogen.vim, after installing it, simply copy and paste:
cd ~/.vim/bundle
git clone git://github.com/phleet/vim-mercenary.git
Once help tags have been generated, you can view the manual with
:help mercenary.
Mercenary is (c) Jamie Wong.
Distributed under the same terms as Vim itself. See :help license.
Heavily inspired by vim-fugitive by Tim Pope: https://github.com/tpope/vim-fugitive
This started out as a fork of fugitive, but I eventually discovered that the differences between git and mercurial while minor in functionality are vast in implementation. So I started from scratch, using fugitive's code as a reference but re-implementing everything to be less of a monkey patch for mercurial.