Advantage- it looks more natural and the discus feel more secure. I think amazon swords look sweet with discus, and they are easy to keep.
Disadvantage- you can't get everywhere to clean and you want the cleanest water possible while your discus are small.
I personally only have my plants on driftwood, so I can pick them up and syphon under them. No more work for me then there would be if I had fake plants.
Depends on your definition of a planted tank, sometimes they can be tons of work. Any idiot can do water changes, but when you have a tank running on co2 and dosing..exc it is with out a doubt more work. Basic plants and driftwood, they are easy, but I'd wait for your discus to get a bit larger if that is one of them in your avatar.