When we do code reviews, one of the major things we're looking for is whether the commit messages are good. Unfortunately, a pull request in Stash doesn't show the commit messages. My best option is to use the Commits tab and open every commit to look at each commit message, one at a time. The end result is: Because this is too cumbersome, we tend to not do it, and a lot of bad commit messages go unnoticed.
I think the Commits tab, under the list of commits, it should show all of the commit messages.