Summary: No it doesn't have Image Stabilization. Yes it is difficult to shoot @ 400mm for the first time. I have to shoot at least 1/400 and usually try to shoot 1/640. Autofocus is noisy but usable. It's a well thought out lens - with a zoom lock @ 80mm, included hood and bag and a decent tripod mount. For the 350 i picked this lens up it's an incredible value.
Summary: I am a devoted Tokina customer! I have had negative experiences with Tameron and stay away from them. I am a sports photographer and having a lens that is well built and has quick performance is utmost for my profession. Tokina are excellent lens and most of the lens I own are Tokina. I only wish they would make this lens with an f/2.8 aperture! I am well pleased with the pictures as long as I don't have to shoot in low light.
Summary: I bought this lens after trying a tameron 100-500 and returning it to the store I bought it at. I exchanged the Tameron for the Tokina 80-400mm f4.5-5.6 AT-X 840D, a hoodman loupe, a 72mm uv filter, and a tamerac adventure9 camera bag. That was the difference in price. I am happy to say am very happy with this lens. Its build quality is rock solid, and the size is very convenient to carry around.
Summary: I've owned this lens for about 6 months now and continue to be amazed at the image quality from this super compact beauty. In fact I owned the Canon 100-400L at the same time so have a great basis of comparison. AF speed is the same for both. The IS on the Canon was nice, but at this focal length I generally use my monopod or other support aid and the IS didn't produce better images at 400mm.
Summary: Love this lens. Compared to others that can zoom out to 400mm this one is compact and lighter. Don't get me wrong. It isn't a light weight. Tokina makes excellent glass. This is my second Tokina lens, the other being a super wide angle 11-16mm lens. This lens sometimes gets mixed reviews but it is all about getting the results you want and knowing about how to get them. The auto focus seems fast. enough but isn't as fast as some of the newer lenses.
Summary: Auto focus tends to hunt for focus on cloudy days. Its a bit heavier than my Nikon lens, Overall, I am very, very happy. I used this lens in Peru and AK… Most people stated that they look like professional shots.
Summary: This is not a technical review. Just my personal observations. I've been taking pictures since I was 21 -- Pentax Spotmatic and then Canon F-1. I'm not a professional but I think I know what a good image looks like. I purchased this lens with some trepidation. First the price did not indicate a great lens and there were some iffy reviews. Also it doesn't have VR. I took a chance and bought it to replace a lens that didn't have enough range. Its mounted on my D300.