Comparing iPad calendar apps at a glance | iMore.com:
Most are pretty good. One looks like no designer really cared to do much design. As with the iPhone versions, that might be because there’s a split between apps designed for iOS users, and for users who prefer functionality over form in the best old Windows Mobile sense of the word…
I’ve been trying to find a good Calendar replacement. Finally there is an Mac, iPad and iPhone version of Fantastical App.