I am really curious about other people experiences and choices.

After a long scouting, I found ZCS to be a really impressive solution, maybe the only real alternative to M$ Exchange.

I'm very interested in opinions and case histories from users having already deployed Zimbra on their infrastructure or planning to do it.

Both Community and Network edition cases are appreciated, pro and cons explained too :)

Zimlets, addons, useful skins, Zimbra Desktop and other apps or mobile integration use case too of course.