This lens gets a lot of grief because it's wimpy build quality. But it's fine for the environment it was designed for: the studio.
The selling point for this lens is that it gives a soft effect which, if used properly (f2.8 at setting 1, or f4 at setting 2), is just about impossible to get with a screw-on filter (even the big $$$ filters) or in post-process via PS plugin, etc. BTW, the best SF filters cost as much as this lens. I use it not just for portaits, but still life and certain landscapes as well. It's very sharp when used as a standard short tele and could be an excellent travel companion (weighs nothing) along with a wide prime. Just don't drop it...