I have and found the technique more trouble than what is worth, might as well just make a mask and be done with it. Is good if you have small areas you want to work specifically, but something like the example he shows of ths sunglasses, that takes way too much time and can be acheived easier with a mask. Not a bad technique, just too time and effort consuming IMO.

Gitta say, though this is the best book by far on darkroom tecniques.