It's not immediately obvious that you need to set up an account and host your calendar on their website. That's the first bummer, but not a huge deal. I was able to get my .ics feed working fine within their system.
The real deal breaker for me is the visual appearance of this calendar. It looks like it was built in 1998. I will take an embedded Google calendar in an iframe over this any day of the week!
Sorry for being harsh, but seriously. Get some design help for this!