I watched it and really did not think much of it. She tried to do her little version of being crazy like Tom on Oprah - no she did not jump on the couch (although she did joke about it) but she was gitty and awkward. Dave kept playing the age joke and then asked about Tom's height. They were playful in their interview and my favorite part was when Dave asked if we had to see one movie, what would Katie say we should see, Batman or War of the Worlds.... She was all smiles.
Defamer has more on the jokes and Letterman has a clip on their site but it does not work on macs..... Also, Jossip points out that Katie also could not answer the easy question of how the 2 met.... You would think this would be the one thing they would have decided on when they began this affair.