For Inky (http://inky.com) we had to devote a bunch of Gimap-specific effort into explicitly syncing flags, for example, because Gimap simply doesn't notify clients of flag changes. Inky has to poll Gimap for flag changes rather than passively learning about them via IMAP IDLE.
And the treatment of labels as folders is a mess for IMAP clients, as is the All Mail folder, which -- if not handled properly -- effectively generates a duplicate of every message in every folder.
But Gimap does work reliably in our experience. It's a bit slow, but it's less broken than IMAP servers run by other major providers (who shall remain nameless).
"I have yet to find any email app on any platform that I can't swear at daily."
I've been using mutt for many years and have not found a single bug or issue. It's fast, powerful, ridiculously configurable, and never surprises me.
[0]http://lee-phillips.org/gmailRewriting/I've seen some bugs over the years, but very very few. I wouldn't use anything else.
I run mutt on a distant server, so I wrote a simple attachment handler that can save or view attachments locally. Despite my wishes, the real world does occasionally send me photos. :)
"the real world does occasionally send me photos."
Dealing with the real world, while using mutt, is made easier with muttils: http://lee-phillips.org/muttheaven/