It is a very good lens, inexpensive, many folks think it is as good as the 70-200 in comparable ranges. You lose the speed and build quality, but it sure is a lot lighter to carry around.
I use it in my boat when out looning for flight shots.
I have a 70-200/2.8 VR1 and i have been thinking of replacing it with the 70-300 for my forthcoming Yellowstone wintertrip. As it is lighter and has a bit more reach. Any opinions about replacing the 70-200 with the 70-300?