If I'm right the build quality and the image quality for this lens is not very fantastic.
More for newbies who want to give zoom lenses a try.
Wide open its only f4.
Compared to 70-200L which has till f2.8
Usages for this kind of lens might be for sports... depends actually.
Cheap does not mean crap. I recently went for a an overseas photo shoot with my $100, Nikkor AF 70-300mm f/4.5-5.6G. Results are comparable to the guy next to me using 70~200mm/ f/2.8. We both stop down to f/8. Landscape pics of course.
If you know your lens's limitations, you can achieve great results.
Why bring a Parang, when a fruit knife can also do the same job as killing. ;p