Excerpt: Great lens I have used it for wildlife. This lens has to be used on a tripod, I find that a full Gimbal head is the best for big telephotos. It is a big lens it has a very nice transport case. Its size also makes hard to take on a plane.
Summary: I was initially very skeptical of the worth of spending $17999 on this lens, but with the discount making the price 17996, I say, "Woo-goo!" Sign me up for this bad boy. I've the perfect spot on my roof for the shot into the window of the cute neighbor that just moved in 2 blocks away.
Summary: You can purchase this lens and walk to your next shooting location, or purchase a car and drive there. With the same amount of money, you can only do one or the other. Even still, this is by far the creme de la creme of lenses for DSLRs IMO.
Excerpt: I purchased this 800mm lens together with Nikon D4s in June 2014 and have used the combo on several bird watching trips, mostly to bird hides on wetlands and one trip on a junk to a terns island. It proved worthy of its price and beyond.
Summary: I have used Nikon cameras and lenses for 30+ years. It's difficult to compare this lens to any other that I have used, including the 600mm f/4 VRII. Paired with the Nikon D4s (with or without its dedicated 1.25E TC), it's a dream lens for the wildlife/bird photographer.
Pros: Razor sharp and quick focus, excellent balance, great VR
Cons: The price, but I suppose that you get what you pay for.