I have recently added the EP-EX15 Eyepiece Extender to my 30D and I really like using it. I wear glasses and also have a rather prominent nose. The EP-EX15 makes it easier use my viewfinder and keeps the LCD clean from facial oil. Despite being able to adjust the diopter of the viewfinder, I have never been totally comfortable viewing through it before I attached the EP-EX15.
However, my wife who doesn't wear glasses and who has a cute little nose (one of the many reasons I married her) doesn't like the Extender a bit and claims that she cannot see into the viewfinder at all with it attached.
This is a "different strokes for different folks" situation. If you have any trouble with your Canon DSLR viewfinder (as far as I know - this unit fits all the Canon DSLR cameras) it might be worth trying one of these Extenders.
However, I would buy one from a retailer where I can try it on my camera. You might be like my wife and hate the thing.


