I've generally found that code review first, and rebase-centric systems like Gerrit tend to be much easier to review code in. One of the best parts of this is native support for stacking multiple patches, so people make smaller patches that are easier to review.
Code review in Github feels like a bad afterthought - the space-wasting interface that looks more like a forum thread, the inability to track over rebases, etc.
There is one thing I miss on Gerrit when you push a stack of commits: A central place to talk about the whole of the stack, not just individual commits. This "big picture", but still technical stuff, too often happens in the issue tracker. But where to place it, I have no idea. This stack is just too ephemeral and and can be completely different on the next push.
Yeah, but you can't really discuss the topic itself, right?
I do think this is a weakness of Gerrit. It doesn't really capture "big picture" stuff nearly so well. At least on GH you can read the top-level comment, which is independent of the commits inside it. Most of the time I was deep in Gerrit doing review or writing patches, it was because the architectural decisions had already been made elsewhere.
I guess it's one of the tradeoffs to Gerrit only being a code review tool. Phabricator also didn't suffer from this so much because you could just create a ticket to discuss things in the exact same space. Gerrit is amazingly extensible though so plugging this in is definitely possible, at least.
On a mailing list, you used to be able to write up the big picture in the "cover letter" (patch#0). Design-level discussions would generally occur in a subthread of patch#0. Also, once the patch set was fully reviewed, the maintainer could choose to apply the branches on a side branch at first (assuming the series was originally posted with proper "--base" information), then merge said side branch into master at once. This would preserve proper development history, plus the merge commit provides space for capturing the big picture language from the cover letter in the git commit log.
Code review in Github feels like a bad afterthought - the space-wasting interface that looks more like a forum thread, the inability to track over rebases, etc.