While it is nice that loggerhead shows the diffs for all files on the same page as the revision information this is almost useless if the number of changes or size of the change is quite large. It is hard to navigate around. It would be better I think if loggerhead offered a separate page/url for changes made to each file (ie each file would get its own page which would show the complete diffs for that file). These pages would be linked to from the modified files section on the revision page.
It would also be nice for other reasons. When using bzr-email-notifier (http://launchpad.net/bzr-email-notifier) the email messages sent could contain these direct links for each modified file. At the moment they can only contain links to the annotation of that file but most likely the user would like to see the changes made instead.
Can you try the attached branch? It's not finished, but I hope you find it to be a step in the right direction.
I think the main thing that needs to be done now is to prevent the /revision/$N page becoming too large, probably by restricting to no more than say 100 lines of diff per file and no more than 10 files by default, and ways to see more (numbers subject to tweaking).