Two problems I noticed off the bat with the full-size iPad 4:
1. Sliders don’t display the entire text on the screen, instead cutting into the image or just cutting off.
2. There is some weird overlay image over my buttons on different pages that prevents them from being read. I really have no idea what this image is, but it only occurs on the iPad. Here is a link to a page with buttons: http://mrbenincasa.com/english1/. The buttons are in the tabs, and oftentimes the first tab’s button is normal, but the others (Unit 2, Unit 3, etc.) have the odd overlay.
If you are using WordPress 3.6 you must be using version 1.9 of the Choices theme. Your style.css is blank for some reason so I’m not sure what version you are using but if you have not updated you should do that first so that we can make sure we aren’t trying to fix an old bug.