0 out of 10 points and recommended
There is a new review at Nikonians -reviewed January 23rd, 2006
Entitled Super wide angles shootout The 12-24mm Nikkor, 10-20mm Sigma, 11-18mm Tamron & 12-24mm Tokina
Comes out well.
There is another put up on February 18th (2006) at
http://www.kenrockwell.com/tech/digital-wide-zooms/comparison.htm which must have a hundred pages of details comparing these four lenses. The level of detail is impressive. The Nikon comes out on top, followed by the Tokina (not avail. in Canada unfortunately)