If comes down to money and desk space.
The Intuos3 is very sensitive and also responds to the angle that you are holding the pen. This makes some tools far more lifelike.
It also has a range of nibs.
4.5 x 5.5 means that tiny lines on the screen need to be drawn even more finely on the pad, because it is a lot smaller than the screen. This can be improved by altering the zoom factor but a large pad must be so much easier.
My advice , oft given, is just stay away from the Volito2 if you can afford to. It's ok, but when the nib has worn down it's pretty well finished. A new pen is almost the same price as the whole original system.
People are still turning out wonderful pictures with the mouse, so don't rush to buy, it might be better to save up a little longer for a better pen.
Luck is infatuated with the efficient.