Compact and lightweight 4x telephoto zoom lens ideal for shooting sports, portraits, and wildlife. The newly developed Micro USM makes autofocusing quicker and quieter. The improved zoom mechanism also makes zooming smoother. The front part of the zoom ring now sports a silver ring for a luxury touch.
Otherwise, I recommend getting one of the Canon EF 70-200mm L zooms such as the Canon EF 70-200 f/4 L Lens. The image and build quality of these lenses are much better.
If you care about great image quality and sharp photos, the Canon EF 75-300mm f/4-5.6 III USM Lens is not for you. And Photoshop cannot enhance details that are not there.
Despite its drawbacks, this is still quite a usable budget telephoto lens. It does not carry much of a weight penalty, and therefore has more chance of being in the bag when you want the extra reach that it offers. In its class, its biggest drawbacks are the close focus ability being poor and softness at the longer end.