Put simply, this lens is fantastic. I have just got back from a trip to New York and decided to buy this lens for night shots, and pictures where I really wanted to control the depth of field, and at this, it excelled. It is super sharp, has excellent control over the depth of field, and is light and above all, cheap.
I shoot on a D40 which cannot Auto Focus with this lens, but this was not a problem at all, and whilst you can now get an AF-S 35mm lens which the D40 can Auto Focus, it is £90 more expensive. I also found that as I took more time thinking about each shot as I had to manually focus each time, I ended up taking better pictures, compared to ones I might rush over with an Auto Focus lens.
At f1.8 the shallow depth of field is staggering. Focus on your mouse, and the mouse mat will appear blurry, it really is that shallow! Moving up above f2.8 and above is when the lens really shines, with super sharp images, which surpass those taken on much more expensive lens.
You really cannot go wrong for the price. The only thing worth noting is that on every Nikon digital camera except the D700, and D3/D3x, you are really getting 50mm with a 1.4 crop (due to the cameras smaller DX sensor), making this a 73mm lens. If you really want something a little wider then get the more expensive 35mm AF-S f1.8.
I've said it once, and I'll say it again, this lens is fantastic. If you don't have one, get one!