Nikkor 14-24mm f/2.8G
Wide of the wide. Stellar optics. A dangerous lens for the faint of heart. Ultimate landscape lens.
Everything about this lens is phenomenal. Well, except that it's filter-unfriendly.
Weather sealed like all of Nikon's newest pro lenses, it'll take whatever you throw at it. The front element is surprisingly durable, and it better be. I don't grind it in sand and dunk it in water, but for the times I've needed to clean it off, which is often, it's been surprisingly easy to get all clean and clear.
I love this lens, however, it's on my camera less than I wish it were. It's got a very unique skill set, and it performs impeccably, but it is a specialty child. I find myself using it mainly for situations where I want to exaggerate surroundings or subject, or need to capture more than even God could want in one single frame. It's certainly a lens for extremes, and I keep telling myself 'closer!' when using it. This get's a lot in the frame. In order to fill the frame you have to get REAAAAAAALLY close.
The focusing on this is fast for the most part... mostly due to everything being in focus beyond a couple of feet. This tends to take the cake when I see a starry night. Getting all of that gorgeousness of the heavens in is more important to me than that of the wider aperture of the 24mm f/1.4.
14mm @ f/2.8, 15sec, ISO 6400
Another useful thing is that at the wide 14mm enables you to open it up for quite some time before star trails become noticeable. The longer the focal length, the more pronounced the star trails with the same exposure time. This also plays into camera blur and shake when handholding.
Ultimately, this is a solid, professional lens. Definitely not a lens to flatter people, but to exaggerate other subjects. Though I love this lens, I wouldn't get it as a first lens unless you're going to be doing a lot of architecture, and/or landscapes. You'd probably be better suited by a more versatile focal range (24-70mm or 70-200mm, and for any lens, f/2.8 versions or faster are the way to go...)
Also note that that wide aperture of f/2.8 isn't really going to show unless you get up nice and close!