Around here, the prickly pear fruit is often called by its Spanish name--"tuna." That caused me a little confusion when I first arrived. The wild fruit is collected locally to make syrup and jelly, but I've never been that enthused about it--without all the added sugar, it wouldn't amount to much. I've never tried one of the "domesticated" varieties like Bass showed us--those look delicious!
Saguaro fruit, on the other hand, is delicious--if you can get any before the birds do. When it has a chance to get pretty dried out, it reminds me a little of Fig Newton filling, with the same sort of figgy seed crunch.
Watch out for those "thornless" varieties--all the ones I've ever seen have tiny, rust-colored, fuzzy-looking spines called glochids, which are worse than the big spines. I made the mistake of touching them with bare hands before I knew any better. Bad idea.