It's really clunky for me  hard to make selections when pressing and the keyboard entry is a little whacky too... Although it is FOSS (open source)  so I'm supporting their effort. It's really a nogo now but has great potential. I couldn't find a way to connect to CalDAV servers. I chose the sync from the bottom of the create page and still received the notification that it would be local only. I have CalDAV-Sync installed and that otherwise works with ownCloud. As far as material UI is concerned: I realty like it and if the buttons and such were more reactive (hardly usable] I would have rated higher. I'll keep a pulse on this but no development whatsoever over the last 30 days a/o 03 Dec 2017. Has potential  but don't recommend.
December 03 2016