I have had this lens for about 6 months. I bought it because I was not satisfied with the performance of the 18-55 kit lens that came with my Digital Rebel. I must say that I am completely satisfied with it. It is much, much sharper than the kit lens, and has better contrast and almost no flare even with the sun in the picture.
My copy of this lens is not noisy. I know that many people say that theirs will cause animals to stampede, and whole flocks of birds to suddenly fly away.... I just don't see it. The nose is very low.
I have a 50mm f1.4, and honestly I only use it in very low light. I use this lens 95% of the time. It is a fun lens.
The focus is quite consistent. The bokah is pretty good. If I had one complaint, it would be that the zoom ring is a bit tight, but it has loosened up a nicely since I first got it.
I would definitely recommend it, for the non-professional or anyone on a limited budget.