It's only a partial solution for me. We use Google Calendar via iCal on our laptops. Cozi lets me import the Google Calendars, but only as read-only. If I add an item in Cozi on the NookColor, I have to explicitly export it back to Google Calendar as read-only. I don't know if paying for Cozi Gold would make it reciprocate with Google Calendar. I would actually have no problems if we migrated completely from GC to Cozi, but my husband is not willing to because he publishes his work calendar via GC. I can have Cozi pick up the calendars and view them even when I have no connection, so in that regard it is more usable to me than just using GC via Dolphin. I do agree that overall Cozi is very good, and if you don't have the same limitations as I do, it is THE calendar app to use.
Cozi seems to be one of those apps that gets a bit lost in the shuffle. I've used Cozi for a couple of years and I was really happy to see the app available on the B&N app store. I've tried a lot of calendars that make all sorts of wild claims about how much they can do, but the Cozi suite is really the easiest, most intuitive, and usefull one I ever found. Glad to see other people are finding it useful as well.