Yeah I use it in some places actually but unless I'm missing something, you can't connect to multiple accounts, see them simultaneously and get notifications on all of them.

While we’re still at a pretty early pre-release version, we already do multiple accounts and unified inbox with ownCloud Mail: https://github.com/owncloud/mail

If you do try it, please let us know of your feedback in the issue tracker! :)

(And that is, you can also run ownCloud with the Mail app locally. We’re working on improved caching.)