I would like to add this: There were a number of people who stated that they did not think they would like this lens if they were using a 1.6 sensor.
Prior to digital my favorite lens for doing portraits in the studio was the NIKON Nikkor 180mm f/2.8 ED lens. Not liking the results I was achieving with the CANON f1.8 (another great lens) I went searching for something longer. 135mm translates to 213mm on the 1.6 sensor. As there was no other choice (I do not like zooms...the CANON 10 - 22mm EF-S being the exception) I went out and purchased it.
Good move. (Actually, I also read every review here...so...thank you.)
It performs flawlessly and I am able to achieve exactly the perspective I like and throw everything in the background completely out of focus.
Bottom line...if you are shooting with a 1.6 sensor and desire a great medium telephoto...this is what you want.
I have also used the lens outside and keeping the "ASA" (some learning never dies) at 100 and the aperture at f2.8 am able to get great results.