At work, we use gerrit, whch is well integrated with git and the CI tools.
Though I personally don't write code, I'm often involved in the reviews: the process does work and I did not hear any major complaint from the development teams.
One can give a -2 to +2 vote on a patchset (or a restricted range, depending on the role), and edit the code in place to propose changes.
You can of course subscribe for changes to a repo, or use an RSS feed.
The size of our projects is in the order of 100kLOC each.