I had the first version of this lens, hated it, sold it (Zoom extends the lens from the barrel, less than desired IQ etc...)! As a professional, I expect more from my investment in equipment. This new version doesn't look to be much of an improvement. As someone mentioned Canon has never included IS on lenses below 100mm, but that is no excuse for not innovating. Perhaps the technology to do it didn't exist before; I'm not a lens designer or engineer, so I wouldn't know. Since Tamron has just introduced their new lens with IS, we know the technology exists to do it today and for the people complaining about weight, it seems from the specs that the Tamron is lighter. Not having done it before is just no excuse for not doing it now and frankly I welcome anything that can help improve IQ and low light image capture thus improving the usability and flexibility of this lens.
It just seems to me that Canon is not a company about taking chances and/or innovating. They seem to always play it safe and just add or improve basic features rather than trying to blow their competition out of the water. No XQD or f/8 AF on the 1DX. As I mentioned in a post before, they could have also added the new Thunderbolt I/O on the 1DX as well and since most of the tech is in the cables, it would have been totally possible without adding to the bulk of the camera. I would like to see Canon show some sign that they are innovating rather than copying or playing it safe. Canon grow a pair! You certainly have the ability.