I have used prickly pear or cactus pear in a beer with honey and Jasmine. It's perfume-y, but it was good.
The prickly pear and dragon fruit are cousin's, so I would think it's similar.
With any new fruit or adjunct, I add it to the second half of a brew. Bottle half, experiment with half. It also doesn't require as much fruit or whatever to make an impact to 2.75 gallons.
Let us know hot it goes.