I look at it this way. If I didn't already own the 70-200 f/2.8 VRII, I would definately buy the new f/4.0 and save almost a thousand dollars. How is that you ask? Well, with the new cameras with their much improved ISO capabilities, you can easily get by with a f/4 lens. No need to spend the bigger bucks for one f stop. That,of course, is if the the new 70-200mm is of equal quality to the f/2.8 version.