I used blood orange in a Belgian Strong Golden a few years ago, and really liked the way it came out. I used the zest in the kettle at knock-out, and added the juice to the secondary. I think it was 2 oranges for 5 gallons.
I know the issue that others here are describing with citrus fruit, and I've tasted that in others' beer. However, I've also used grapefruit and Mandarin oranges in beers with great success, and never had that off flavor issue.