It's particularly hard to view and scroll through diffs.

While it allows you to jerk left and right a little, can't even scroll to bottom to use the left/right scrollbar.

This may be very far off, but just something to keep in back of minds; Jira has a mobile client (though it's pretty useless other than viewing content) and serious code reviews you should probably have a laptop/desktop.

iOS 7&8 safari & chrome
Some related tickets include:
STASH-2723 Add User interface nonfunctional without mouseover (e.g. on iPad)
STASH-6864 Unable to submit comments on mobile site
BAM-6519 Add mobile version of Bamboo pages