I own the Ott floor lamp and I love it. I use it for needlepoint, but not for knitting. I never felt the need for it when I am knitting. However, if the light in your favorite knitting spot is poor, the Ott is a good choice.
I owned a needlepoint store and we sold the Ott lights. Overall, our customers loved the Otts, but no one liked the magnifier that some Ott lights have. The magnifier was difficult to adjust and if you moved you lost the angle you were using for magnifcation. Does that make sense? Not sure how to describe that.
Also, check the price of replacement bulbs. Tru-Color bulbs can be $$$. I still love my Ott, but just wanted to pass along some of our customers concerns.