The stylus lets you run any desktop software comfortably, as it doesn't need a low density UI that also considers how the finger blocks the view of whatever is under it.
I don't agree with this. I have a Stylus, and have always had a stylus for just about everything, but the position a stylus forces your hand in is just not as comfortable or natural as resting your hand on a mouse or hovering it over a tablet for touch. Switching from keyboard to mouse is something most people do a tonne, and that matters a lot. And on Windows platforms, I have not found it to be very intuitive for a number of tasks, such as selecting and right-clicking, etc.
I agree it can be insanely precise and fast, and there are areas where it is unbeatable, but for me it comes quite a ways in third place after mouse and touch. In fact, my latest PC tablet has both multi-touch and 2500dpi pen features, and I was finding I was preferring to use my fingertips for controlling the mouse cursor.
It's still really great for drawing though.