The lens just came in (rental), unfortunately a light snow fall has hit and I wasn't able to test TOO much just yet. I'm looking forward to the weather this weekend.

My first impressions is that the lens is heavier than I expected, about 10 ounces heavier than the 28-135. I understand now what people mean by this lens being sharp and having better color straight from the camera. I shot a snowy bog with the 24-105 and 28-135 and i can see the difference. So far, I'm impressed.