Yes, you can take action shots at 400mm without a tripod too.

The pros and cons I mention sum it up: This lens is heavy, especially with the tripod collar attached. It is lighter than other 400mm long lenses, however. The zoom is a little stiff; the focus ring is smooth and silky. This lens has an easy way to switch between auto and manual focus by adding a ring at the end of the lens that allows you to switch - this will come in handy when you just can't get the camera to focus quickly and you want to go manual quickly before losing your shot.

The VR is interesting and works quite well. Nikon advertised you can move up to 3 stops brighter with your shutter than you normally would have to go. This seems to work as advertised. There is a switch on the lens that allows VR to operate in three modes: Off, 'on' and 'on'. The two on mode's vary as follows: The first on mode turns VR on the moment the shutter is depressed lightly. The second VR 'on' mode doesn't turn VR on until the shutter is fully depressed. The VR mechanism can also tell the difference between the user "panning" vs. "shaking". It is reliable and just works.

I took some pictures of the moon in the evening at full zoom and at 300mm with my Nikon D100. I tested the photos by taking shots with the moon center and at varying degrees towards the corners. At the maximum zoom, details and contrast was very nice- I could see details of large and small craters. At 300mm I compared the results to my 70-300mm zoom and this lens BLOWS the 70-300 away. I could magnify/interpolate my images 2x with this lens and still have sharper images than the 70-300mm lens. The 70-300 is much lighter however.

Another nifty feature is a switch on the lens that limits the range at which the autofocus will attempt to seek focus. This is handy if your subjects are 40 feet away since it is very frustrating waiting for this lens to move through it's fairly wide focusing range while your action subject is running away.

Besides this lens having good overall sharpness, the VR really helps make your shots sharper. Whether you're holding this camera in your hand or on a tripod/monopod, the overall vibration is just cut way down helping ensure your shots are clearer.

I also had fun with this lens at a family reunion. With this lens coupled with my D100, I was able to capture details at close range that enable you to count the pores on someone’s face just across the room. At the zoo, this would be very handy to capture an extremely detailed shot of a bird, but be able to back off to 80mm for larger subjects.

I highly recommend this lens. If you can, go down to your camera store and get a demo, you'll be pleased. If you can't find a store to try this out, you won't be disappointed.

Lastly, don't buy this lens from Barnabeez.com (I wouldn't buy anything from them). After I placed the order when the web site said they had it in stock, they called me back and told me there was an "SLR" version and a "Digital" version, the digital version was the "enhanced" version designed to take advantage of the digital camera's sensors for an additional $100. I called Nikon to see if they knew anything about this and they said "nope, sounds like someone's trying to scam you out of an extra $100". They were correct. Then asking them to ship it to me anyway, they said it would take 10 days to get the order processed which is a lie from what they first told me. I ended up buying from Camera's West, a division of ritzcamera.com (or kitscamera.com) - got it right away with no problems.