The result you get from combining a Rotring 600 mechanical pencil, the best mechanical pencil in the world, with a tiny stylus ? The best stylus in the world.
It becomes a slightly worse as a pencil though unless you modify the original cap; without it there is a tiny gap at the top, so the insides either wobble a little, or you have to add a bit of tape which makes it sticky when advancing the lead. I just stuck the stylus in place of the eraser so the whole thing is completely reversible while I wait for my sacrificial replacement caps to arrive.
I also use the end of my pencil to poke my calculator buttons, the stylus makes it less prone to sliding off the buttons and much less annoying for everyone else around :P
Abusing the stylus will eventually break it, but as the cost for one is around 35 cents it really doesn't matter.