I'm unhappy with the approval process being a simple search for "LGTM". I wish GitHub pull requests had actual support for a review process, e.g.:
* open issues to address
* review state, such as "changes requested" or "approved" (along with users that are in each state).
We've been using Phabricator's[1] Differential tool for code reviews and it feels superior to this process, but it would certainly be nice to have an all-encompassing solution for this.