Mainly I would say that it works great for projects with relatively few contributors (like most Ruby gems), but seems to fall apart on very large projects (like Rails, who uses Lighthouse for issue tracking). Everything else about Github is amazing, though.
dhh doesn't sound like he was ever a fan of Lighthouse: https://twitter.com/#!/dhh/status/63366853636009985
Once again: trac is REALLY GOOD and no other project can compete for clarity and all other words form that UX crap. ^_^
Also, what does Webkit have to do with Trac?
Emacs. Tag search. Problem: solved.
My life has been infinitely enriched by the countless hours I've spent, many a dark night, in /usr/src/linux[1], with "Midnight Commander".
[1] A symlink, always a symlink.
As for descriptive names, I agree.