While this lens is usable, it requires a bit more babysitting than most to get sharp images. You really don't want to shoot at an aperture wider than f8, at any focal length. All the way out at 300mm, you probably don't want to go lower than f11.
The focus motor is quite slow if it has to travel far, though focusing does seem accurate.
The front element rotates during focusing, making it quite difficult to use a polarizer or GND filter.
The hood, while secure, is a pain to line up properly and attach.
On the plus side, the lens doesn't cost much. Also, the zoom ring is very firm, so you're not likely to get any zoom creep.