Support for requested reviewers has arrived
Requested reviewers are now fully supported throughout Reviewable! Details follow, including which features are only in the beta so far. Note that you may want to update your custom review completion conditions, if you've got some.
First, requestedReviewers are now available in review completion conditions. The default condition uses requested reviewers in place of assignees if any are specified, tagging any who haven't joined the review yet as being waited on if any files have no reviewers at all. If you'd like to customize this, you can look for inspiration in the updated sample conditions available in the beta's repository settings. (You can safely update your condition even if not everybody on your team is using the beta, it'll work fine.)
Second, there are several improvements to the review list in the beta. It now includes PRs where you or one of your teams are a requested reviewer. It has two new sections: "waiting on me" and "being reviewed by me", to help you further prioritize your reviews. Finally, the hand no longer points at assignees (since that gets messy with requested reviewers thrown into the mix) but rather at people whose attention the review requires to move forward, so you can see at a glance who you need to nag.
Third, again only in the beta, the sentiments section at the bottom of the top-level discussion now has indicators marking who's being waited on, assigned, or a requested reviewer. You can also manage requested reviewers with the new ±reviewer:@username directives (similar to the ±@username assignee directives), and as usual all directives work in comments originating from GitHub or email as well. (You cannot use directives to set requested reviewer teams at this time — I can add this if there's demand.)
The beta is coming along nicely and I expect it'll get promoted to stable pretty soon. In the meantime, as always please let me know if you find any breakage!