The application looks good on the iPad.
One thing that bothers me is that Inbox, Achievements and Sites view are presented modally in a form sheet presentation style. This creates a disjointed flow, where a modal form sheet appears, the user makes a selection and the form sheet disappears.
I feel a popover would work better in this instance.
If you are using iOS8 SDK, this is very easy to achieve and requires little work. Change the presentation style to popover, and fill in the information under the
popoverPresentationController. Now, on iOS8 Inbox and Achievements will be presented as popovers (using the same presentation and dismissal API).