I've been using Nikon's first entry level full-frame camera, the D700, for about a month now and I have to say I'm extremely happy with it.
Basically, what we have here is a D3 jammed into the smaller body of the D300. Inherited from the D3 are the full-frame (or in Nikonese, FX) sensor, the EXPEED image processor, the super fast Multi-cam 3500FX AF, and the excellent 920,000 dot LCD.
First off let's talk about the sensor. The D700 boasts a 12.1 Mp, 36 X 23.9mm CMOS sensor. Nikon's refusal to take part in the great megapixel race has paid off. This sensor has the largest pixel pitch of any full-frame camera on the market (8.45µm) which translates into almost no noise up to ISO 3200, and very little noise at ISO 6400. From the D300 the D700 also gets a built-in dust reduction system to help keep those pesky dust specks out of your images.
The D700 also boasts an DX mode for those who have digital only lenses and may have to wait awhile (after shelling out 3G's for the D700) to purchase FX lenses. Although you take a hit in resolution, 5.1 Mp as opposed to 12.1 Mp, you still get the benefit of the large pixel pitch and resulting low noise. Even at 5 Mp you have enough resolution to print a 16 X 20 inch print. I've actually found myself using the DX mode when using FX lenses for that added "reach". I'd rather compose the image in camera than crop later. I've been using this feature so much that I've programmed my AF-L/AE-L button to allow me to switch between FX and DX. The only drawback to using the DX mode is that the D700 doesn't mask out the unused portion of the frame, it only gives you a black square to go by. This is OK at the time of shooting, but if you put your camera down without switching back to FX it's easy to forget and you find yourself composing for the full frame but only get part of it.
Unlike it's big brother the D3, the D700 has a built-in flash. Although some pros may frown at this feature, I love it. The built-in Speedlight allows you to control off-camera Speedlights such as the brand new SB-900 wirelessly using CLS. This saves you from having to buy an SU-800 commander or using one of your SB-800's or 900's as a commander.
New in the D700 is the ability to set the LiveView feature to the Func. button (or the Preview or AE-L/AF-L button). This allows you super-quick access to the LiveView feature.
Like the D300 and the D200 before it, the D700 has a heavy-duty magnesium alloy weather sealed body and the thick and comfy rubber grips. Needless to say the D700 feels like a solid professional camera. Following in the footsteps of it's predecessors most of the buttons and layout are the same with a few addtions. If it ain't broke, don't fix it folks... Nikon has always (in my opinion) had great intuitive layouts of their menus and buttons and the D700 is no exception. I try not to get my cameras wet, but I was caught in a freak rain storm the first day I got the camera. It got soaked. It still works. 'Nuff said.
Another great feature is the fact that you can use the D300's MB-D10 grip with the D700. Way to go Nikon! I get tired of buying a new grip for each new camera. The D200 grip was plastic and lacked a multi-controller. The MB-D10 is magnesium and has a multi-controller, it actually feels like a part of the camera not just an add on. Although the D700's frame rate dropped to 5 fps (as opposed to the D300's 6 fps) When you attach the MB-D10 and use AA's or an EN-EL4 battery your frame rate is back up to a blistering 8 fps, fast enough for almost anything you need to shoot.
The image quality of the images from this camera are outstanding, especially when the body is paired with one of Nikon's pro lenses. The high ISO capabilites of these camera are no less than amazing. From ISO 200 to ISO 800 there is almost no noise at all. At ISO 1600-3200 there is slight noise, but this is easily taken care of in Photoshop. ISO 6400 is quite usable for medium sized prints. The D700 ISO goes up to a ridiculous ISO 25,600, although it can get shots in near darkness they are pretty damn noisy to say the least. The D700 precision 14 bit A/D converter gives pretty good dynamic range. The D700 also allows you to shoot in 12 0r 14 bit RAW which can help you deal with those tough shots by providing a little more image information so you can recover blocked up shadows in post. It also helps to reduce posterization in the shadow areas.
Nikon D700 w/50mm ƒ/1.8 ISO 1600 1/60 @ ƒ/1.8
Although, the D700 is a great camera it's not without it's faults. Most of the faults reside in changes that Nikon made from the D300. There are no major faults that would prevent me from buying another D700 for a backup.
1. The CF card door is badly designed, it's already popped open on me a couple of times. Nikon has removed the lever to make room for an info / quick settings menu button. The door design and the Quick settings menu are derived from consumer cameras and really don't belong on a camera of this caliber.
2. The rubber flap that covers the USB and HDMI outs isn't a snug as on previous cameras. This too has popped open a couple of times already. If you're out shooting in bad weather this could be a potential problem.
3. The redesign of the CF card door has left less room for the thumb grip. The D300 is much more ergonomically correct.
4. Like the D60 the menu option to set the USB to mass storage is removed from the menu. This means that my camera doesn't show up on my computer and I have to use Nikon Transfer to download if I don't have my card reader (which I sometimes forget to pack when on a trip). Using Transfer adds another step to my post and seriously slows down my workflow.
5. The camera doesn't automatically switch to DX when using 3rd party lenses. Since I've finally sold off all of my DX lenses, this really isn't that big of a deal to me, but it could be for some people.
Other than these minor quibbles the camera is top-notch. It's a perfect camera for pros and amateurs alike. If you were thinking about a D3, but the camera was too big, the D700 is for you. If you already have a D3, the D700 makes a perfect backup. If you're a natural light shooter and you find yourself frustrated with noisy images, you've found your camera. All in all, this is one amazing camera. The D700 is well worth every penny.