Treated myself to a new telezoom, a 2.8/70-200, especially because I wanted the large aperture. And boy, does it make a difference in the viewfinder! With such a clear view, you can use manual focus much better. However, this is also my first lens with HSM focusing and that is impressive too: smooth, silent and fast; so you don't really need manual focus.
But the main reason for wanting the 2.8 opening is that it reduces the depth-of-field so you can have very selective focus. Hope to make use of that in the coming days--and coming years!
The disadvantage of a big opening is that it is a big and heavy lens. Yet even here I was pleasantly surprised: the 1.3 kg have a very good handling, nice balance with the camera and you can use it very well 'shooting from the hand', without a monopod/tripod.
For the moment then, just a little example of what may be done with such a lens: a random insect on a random flower in a random place (the backyard of my house). The lens has a good bokeh, I think. I am pleased with this new toy!