All the buttons at the top of the default monthly calendar don't work. That little 'loading' wheel will spin all night if you let it -- and I did. The page to the next month or year never comes up. Ditto for every other button. All you can see is the month you're in and the events in it. If you want to see next month, forget it.
However, when I add a new event in a different month and select View Event I do get to see the event's page and button to Return to Calendar will take me to the right month. Great for me, but not for any of my viewers (potential customers).
This calendar looks great and promises everything we need, but it under delivers. I hope they fix these bugs soon.