Assuming QuickCal correctly interprets your event description, you just press Return to immediately create the event. Alternatively, press Command-Return to create the event and open it in your preferred calendar program. The latter option is nice if you want to perform another task in your full calendar program, but it's also useful if you need to add a note to your event--you can't add notes from within QuickCal.

Similarly, unless you use Google Calendar calendars--and sign in to your Google Calendar account from within QuickCal, not within iCal or BusyCal--QuickCal doesn't sync your events directly with your Internet-hosted calendars. It instead uses iCal to perform this task, which means iCal must be running when you create new tasks (or at least must be launched sometime afterward to sync). I found this to be the case even if I set BusyCal as my preferred calendar program--I still had to keep iCal running for QuickCal-created events and tasks to appear in BusyCal.

QuickCal does have a few features you won't find in Fantastical. My favorite is that when creating a new event, if that event would conflict (overlap) with an existing event in any of your calendars, QuickCal displays an alert in the event-creation box and turns the Create Event button from green to red. Another is that while both programs can automatically set alerts for new events, QuickCal can create additional reminders for events further into the future. For example, you can configure QuickCal so that all events get a one-hour-before reminder, but events more than a week away also get a day-before reminder, and events more than a month away also get a one-week-before reminder. (QuickCal's alarms are simple notifications. It doesn't support iCal's other types of alerts, such as sending an email, running an AppleScript, or opening a file.)

QuickCal's biggest advantage, for some people, is that it supports viewing and creating tasks. Type todo at the beginning of an event description, and QuickCal creates a new task instead of a calendar event, complete with a due date if you specify one. Tasks you add to your calendar (either using QuickCal or within your normal calendar program) appear at the bottom of QuickCal's menu.

That said, besides the Fantastical advantages I mentioned above, Fantastical displays a full, browsable calendar; lets you view events for any date; lets you search your calendars; lets you create notes for events and edit events directly; syncs directly to any CalDAV calendar; works with Entourage and Outlook calendars; can remain onscreen while you work in other programs; lets you invite people to events using your Address Book contacts; and supports AppleScript and OS X's services.