Differences between cooking a whole duck vs chicken or turkey?
With chicken and turkey, the most important "trick" to cooking it is to make sure the dark meat gets done before the white meat dries out, and to make sure the skin crisps up somewhat.

Duck is all dark meat, and has a thick layer of fat that must be rendered out. There is not a lot of danger in drying out the breast meat like with a chicken.

Like Martha said, it's best to make a few shallow cuts in the skin over the breast (don't go all the way through to the meat) to help the fat render out. A simple (western) roasted bird would be cooked at 350&deg;F for about 1 hour 45 min, with the oven turned up to 500&deg;F for another 15 minutes to crisp up the skin. There is a LOT of fat rendered out, so it's best to roast in a sturdy roasting pan, on a rack (so it doesn't sit in the fat), and drain the fat about an hour into cooking (save the fat, though; it's delicious).

Personally, I think duck is easier to cook, but it's definitely different from roasting a chicken.