I've shot with 2 samples of this lens, one as is and one with the Kirk tripod collar attached. The lens is big, heavy, and excellent. Handling is an absolute dream when you use it hand held, but hopeless and indeed dangerous when you mount in on a tripod because the lens is so long and heavy that it could warp your lens mount. The new version of this lens solves the problem by introducing a tripod collar with the lens. It shares the same optics with the new, two-touch version of the lens, with excellent performance equalling that of primes at most apertures.
Light fall off is noticeable only when used wide open.
This lens is awesome to hold and use hand held. Some people don't like the push-pull zoom, but I'm very comfortable with it. The one-touch, and push out to zoom concepts are a bit strange at first, but once you get used to it, it's fine. The lens looks and feels almost like a manual focus Nikkor. Rugged and constructed to the standards required by professionals who subject their gear to serious use and wear.