I am very pleased with the lens. In fact, it has no analogues in the 17-55 range, because what is called an alternative to this lens is inferior to it either in terms of optical characteristics or functionality. Different pros: Constant aperture, fast autofocus, very sharp, contrast, good performance stabilizer, supports E-TTL II flash mode, aberrations are minimal like L-lenses. Cons: It’s hard to find a native hood even in Hong Kong, and besides, it’s expensive. Expensive filters for 77mm, and the lens itself is not cheap.