We've recently switched from BitBucket to Stash and we really love the improvements. Nonetheless, there's one BitBucket feature we deeply miss in Stash - AJAX notifications about changes to pull requests, like added/deleted/changed commits, new comments, approval/disapproval. I happened to ask colleagues for approval after they've already done so because I got so used to having been notified by a little AJAX popup in the lower-right corner of the window of the change that happened.
Ideally everything would be updated without requiring page refresh: comments, approval status etc. but at the very least a notification about what's changed so that we know we have to refresh the page is needed.