The Cal app is essentially a calendar app that connect to your existing calendar services. So when you first install, your appointment entries will populate Cal naturally. Additionally you can connect to your contacts so appointments can include them as needed for event invite or email communication.
The Calendar shows only the calendar week on top and calendar month if you drag it down. The bottom part shows the day appointments and impending tasks, which links to Any.Do.. This convenient integration required Any.Do to be installed and login credential to be entered. The app uses some graphics themes for the background that can be set in the app settings.
Set aside the elegance of its UI, Cal shines when you create appointments. The app uses location-based to offer location, maps, etc.. to complement your appointments as well as offer to add people you most likely to include to your appointments.
With emphasis on simplicity, the App left out other features such weather, agenda view, list view, week view, conference call formatting, etc.. which are needed for productivity.