Summary: The D3s is an amazing workhorse camera. It has changed the way I go about taking pictures due to the high ISO ability. I shoot mostly low light action. I have probably shot more at 10,000 and 12,800 ISO than any other setting. It is just stunning.
Pros: High ISO Performance. Blows EVERYTHING out of the water in this area. No other camera made right at this moment even comes close. In a league of its own., 12megapixels. This leads to smaller files and is easier to deal with for event work, Very fast autofocus and very reliable tracking, Big serio...
Cons: No flash or other means to trigger the Nikon CLS for off camera flash., The color Red and Magenta. Tends to blow them out badly under certain conditions., Big and heavy but this is also sort of a plus depending on how you look at it., No AF tracking in video
Summary: This is the best Nikon body you can buy, if you can find it. The earthquake in Japan knocked out the D3s factory. If you can get this, you will have the best Nikon body on the market. It takes amazing pictures and work great in low light. You can use it in any situation.
Summary: I tried to resist buying this camera when it was first released, and then I went on a photo shoot, photographing Sandhills Cranes in the Platte Valley, with a guy who was using one. The problem with Cranes is that the best photographable behavior occurs right before sunrise or right after sunset.
Summary: I ditto what most others say here. The Camera is magical. So lets not beat this point to death. I'd be just restating what they say anyways. my point is this. Make sure you have a credit card set up to buy this. I tried to used my debit card and it would not let me purchase this camera.
Summary: [June, 2012 update] Probably everyone else who knows digital photography also knows about Dfine 2.0 ; I didn't until just recently. With the D3s, I can easily shoot at ISO 6400 and up then use Dfine to remove the grain.
Summary: Everyone raves about this camera, and it is easy to see why. But I want to mention Amazon is awesome as well. There has been no stock of this model available anywhere. I asked B&H how long if I actually placed the order and got a very poor response.