Pros:

Fast focus, strongly built with a solid feel, sharp throughout, a well built lens hood, cheaper than the Nikon 12-24mm f/4 and in my opinion just as good

Cons:

A bit on the heavy side, some problems with flaring, the lens hood takes up a wide space in the camera bag, the ring to switch from AF to MF is rough, DX format makes this a 18mm-36mm

Examples:

Here is a gallery of architectural images taken with this lens only: Click Here