Bought this guy to replace my 55-250mm. While the 55-250mm had its good moments, I decided to get the 70-200mm hearing about how sharp this lens is. I thought my 55-250mm was pretty good, produced some sharp images, but I wanted better IQ all around. Other than build quality, and superb AF speed, I am a bit disappointed. I did some tripod shots at boring text comparing the two, and the 70-200mm was only a hair sharper. I brought it outside today to the park to take some random photos and honestly, if I were to blindly compare the 55-250mm to the 70-200mm I couldn't tell the difference.
I am on a t2i and I realize that if this lens were on a FF, it would be a bit sharper but everyone says the lens provides the biggest difference in IQ.