Instead of writing a long-winded review, I’ll opt for simplicity with three reasons to use Calvetica.
Add an event with three taps. Tap the day, tap the time, title your event and tap Done.
Syncs with the built-in calendar. Events created before you purchased Calvetica appear in the app. Appointments created with Calvetica appear in the built-in calendar(s) of your choice and will get synchronized across all devices if you’re a MobileMe subscriber.
Finally, use Calvetica because this is gorgeous: