Initial start-up was slow (40 messages, of varying ages, set to sync 1 week).
Fairly snappy after that. Having used it less than an hour, I have not yet fully explored it, but:

  • Compose works as expected (text only is OK by me).
  • Browsing is OK. Default view seems to be by conversation.
  • New mail alert comes up OK. I would prefer on-demand rather than push.
  • New contact on web appeared on my phone quickly during compose.
  • Ouch! No contacts I removed my account from the built-in Android mail app (didn't want conflicts with Zimbra app), and this seems to have removed all of my contacts and calendar entries, and the Zimbra app did not re-add them.

I hope some of the above are changeable via settings I have yet to discover?

I tapped "invite". Added an entry ½ hr hence, and added a colleague.
The alert came up in due course, but never did appear on the web app.
I thought this was a bug, but seeing that the calendar is different than my web/enterprise one, it makes sort of sense. Nothing in my sent folder indicates my colleague was invited.

The lack contact and calendar sync is an absolute show-stopper for me.
Going back to the built-in mail system with Exchange sync. Too bad.