So I'm not quite sure how to rate this. I bought it solely so I didn't have to take my professional quality L lenses on vacation to the mountains camping, or just out when we go see family and that. I feel more comfortable leaving the big $$ lenses at home.
So I knew when i ordered it I wasn't going to have the same quality. I knew that going in. So here are my thoughts. I found the auto focus to be quick and quiet. It focused where I wanted it to. Now, I manual focus probably 95% of the time, but when I got it, i played around with the auto focus just to see how it reacted, and I was rather pleased.
As far as the quality of image, I have found that when i am shooting distance the images turn out sharp. The closer I get, the softer the images become. Again, I knew I wouldn't be shooting with an L quality lens, but I was a little disappointed with the softness that it is providing. But, it's not so bad that it is going to ruin a family picture. You aren't going to be entering a major competition with the results.
You can get some pretty good "macro" style shots. Always remember you can crop as close as you want, and depending on what camera you are using, you can probably crop even closer than others.
So, for the money, i would like it to be a little sharper on the closer shots, but like i say, it isn't a deal breaker. Over all it's a fun lens. I don't have a need for any other lens when i take it out to use it for my purposes.
For a professional lens, i would say save your money and get an L series. Always get the best lens as you'll be getting one eventually. I have a 28-135 that provides a much sharper image, but this is still a very nice entry level lens.