I have purchased both... I think the UDP, when on sale, is the best value. Odyssey is great since she has a lot of options.
We did two nights in Chops, two night in Giovanni's, two nights in Hibachi and one night in Wonderland. If I was cruising Odyssey again I'd do it the same way and pay the uncharge for the hibachi. It was very, very good.
For lunches, beyond the specialty restaurants on sea days, you have the option of Playmakers which has great food and the English Pub. Odyssey's pub is the only one, that I know of, that serves food. We ate there for lunch at least three days, if I remember right, on our 8 day cruise.