I use it a lot (Hey, I like it. :)) but I know if I push the camera out too far I get fuzzy skies.
Now, what I've been doing is have the camera (usually) around 55mm focal (sometimes more, depending on what I render), and enlarge the sphere to push it further back so I don't get pixellated skies.
Reason for this is, if I pull the camera in to about 15mm (which would be great for the sky), it distorts the face of the figure I'm rendering.

I've tried to mess around with the perspective/focal, but they always go to the same value.
(What is the point of that, exactly?)
Focus distance.... haven't had much luck with that either. (I really need to play more with it, and fStops too.)

Now the question is, is there a way to render without a distorted figure, but a great sky, without resorting to what I'm doing atm -- or is that the right way to go about it? (Enlarging the sphere to push it back)

If you're not completely fed up with explaining things... I'd love to see a tutorial on camera settings, with or without the env sphere. :)

Silke