This is a fantastic app. I've found it to be much easier to use than iCal, and obeys more Mac OS conventions as well (iCal's a bit of an odd duck).
My only request is support for adding files to items on days, or to be able to launch a file based on a day or time. That would rock.
Regarding the half star rating because someone didn't like the trial version's restrictions, that's just being petty. Especially considering that the App Store doesn't even allow trial versions. For developers to offer a trial these days, it means they're going out of their way to offer something to the user that *most* developers don't offer. If you don't like it, that's fine. But your half star 'rating' doesn't help you, or the developer, or the Mac community.
It only discourages developers from offering trial versions at all.