I've been using GitHub's code review features a bit recently. Something I really like is the ability for a reviewer to quickly make suggested code changes that the reviewee can can approve with a button push, instantly committing them. This saves a lot of time, especially for small, relatively insignificant changes.<p>Overall though I find GitHub's code review a bit fiddly and awkward, and it's features aren't "easily discoverable". Using the feature I mentioned above as an example, it's rare that reviewees actually know about it, or see and use the "Approve" button.