I had one. The price used to be $490 a couple of years back.
It is light, build seems good. Balance very well on manual cameras.
Sharpness is quite good when stopped down to f8 or 11. Contrast is also good. Vignetting is strong wide-open but almost gone (at 19) at f5.6.
Sometimes sharpness is not everything. It is cheap, light and if you are just doing hand-held photography, it would differ little from much more expensive glass. Distortion is quite strong though, but so are any wide-angle zooms.
Only problem is that you need to buy the hood separately.
BTW, my results are from film, not digital.
I am using one. For the price, its very good. Sharp and autofocus is fast. But my friend keep harping at my ear that it is not 2.8 and what 2.8 can do, this and that. But hey, less than 400 what do u expect. If you don't need a fast lens, this serve its wide angle purpose very well
There are photographers who are probably just equipment collectors. If low light performance is needed, then maybe a prime is better for the money. If super sharpness is required for that 16R enlargement, then medium or large format should be used, not 35mm.
My wife was criticised by her friend for using a "amateurish" F601 and tokina orange ring 28-70/2.8 by her "pro" equipment colleague. I would like to say "Show me your pictures!".