I use one very similar to that on my road bike. The armrests on mine flip up, out of the way, when I'm not on them. Aerobars definitely give you more postions to be in, although they take some getting used to. I'm not sure I'd call them "comfy". Steering can be very squirrely. You have to think ahead if you're going to brake or change gears because you have to get out of them and back onto your regular bar.
The advantage really comes when you're going into a headwind or along a straightaway. I find that I go 2-3 mph faster without a lot of effort.