The Nikon 18-35 is a consumer-grade ultra-wide zoom (the Nikon 17-35 and 16-35 are the comparable pro-level lenses). The 18-35 is much cheaper and lighter than the pro lenses, and the build quality is a little less robust. Having said that, the 18-35 is an outstanding lens for the price, and is very easy to lug around all day on trips. It is well-made and can easily handle the abuse of travel and daily use in basically any environment. The lens feels perfectly balanced on a D700, and I tend to carry that combination all day when on trips.
Performance is surprisingly good, with great saturation and color. I usually shoot mine wide open at 18mm (f3.5) for a little background separation, and while the corners are definitely not sharp, they're not distracting. The corners get better a few stops up, but they're never really pin-sharp at 18mm. At settings above 18mm, the softness goes away and the images at 24 to 35mm look excellent. This lens works perfectly for most street photography, family snapshots, action photos, nature shots, and travel photography, but does not fare as well for architectural or true landscape shots due to the softness in the corners, though it's still usable if you're very careful about what you put in the corners. Autofocus (with the D700) is fast and accurate enough for action photos of my golden retriever at close range.
I've been using this lens with a D700 for over a year now, and if I could improve one thing about it I would skip the corner sharpness and go for slightly faster glass. This lens really only makes sense for FX bodies, and if it were just a little faster it would really be perfect. As it is though it's tied with the Nikon 50mm f1.8 for my favorite lens. It's tough, light, and takes beautiful images for less than half the price of the pro lenses.