Looks good. Haven't downloaded to test in detail, but looks nice.
Were you aware there was already a calendar module? It pretty much died, but there might be some useful stuff in it.
Also, not sure since I didn't download and test, but having a smaller widget version of the calendar would be good. Users like to add calendars in the sidebar of their page and when you click on the exact date, brings up more detail stuff.
Still I would like to use the google calendar widget on websites, but you know some dont want their visitors to navigate away from their website for any reason, in that case anyone can use this module. And this can be also used as a diary too.