branches, tags and tree views
It's kind of odd that tags and branches take you to changesets. I'd expect a view of the source tree for the changeset of the tag, or the current state of the tree for a given branch.
Bitbucket doesn't seem to have a concept of browsing the entire source tree at a given changeset at this point, rather than browsing current files and individually seeing their history. Does that mean there's no way presently to see files that were deleted?