Some core features that you may be interested
A feature many of us lack in our Mac's. Available right away on one click. Lightweight and efficient. Displays all data and events from your system Calendar but does not occupy the whole screen.
Yes, it can grab all your events from Facebook. Of course only if you need them.
Google calendar integration.
Probably you have google account. Most of us have it, no? :) If you use google calendar to track events, you may find google cal integration useful as well.