I used hg before moving to git and always preferred the clean, single language implementation vs the scripts and general hackish nature that git offered as an alternative. As a result, it was a nice perk for a long time that hg worked much better than git on Windows.
Docs:
https://selenic.com/hg/help/revsets
A complete example, which appears to have some popularity in Mozilla:
http://jordi.inversethought.com/blog/customising-mercurial-l...
edit: Sorry, the --decorate part would be with template, the --all is kind of like a revset, and the --graph part is well, --graph.
Except for the --graph part which would be accomplished with --graph of course
> Revsets are kind of like gitrevisions(7), but much more powerful.
And easier to read and write too.
Yes, it's a way to select sets of revisions by filtering and merging existing sets.
> and are the queries thus-specified ones that have direct analogs in git and can be done in git using git's API?
I don't think so, not all of the filter operations are available, but more importantly I don't think git supports arbitrary sets of revisions, only fairly basic relatively continuous ranges (that's the idea I get from gitrevisions(7) anyway)