It's a real desert, maybe 3-4 inches of rain a year. Long periods with no rain. Technically it is part of the Sonoran Desert. And pretty hot in summer as it's inland. That's probably not the best season to visit.
The native agaves of this area are A. cerulata and A. shawii (found just to the north, not actually in CataviƱa). The shawii plants there are 2-3 times the size of the ones we have here, and they were putting on a pretty great show with orangey yellow flowers (winter is their flowering season).
As for wildlife, some friends of ours were trying to figure out how the blue fan palms down there are pollinated and the seed dispersed (ecology questions) so they collected scat from all sorts of interesting animals (up to and including cats) who came by to snack. Apparently the fruit is highly edible. I was given a whole bag full of predigested palm seeds from their travels.
There are bighorn sheep (legendary) but you're not likely to see one.