As M. Potter says, this is meant as a lens protector, and it works just fine in that capacity. I've noticed no changes in my photographs. I don't know about it helping with haze or whatever, but if you want this as a basic cheap lens protector it works fine in that regard.
But make sure to check your lens diameter before buying! You can either find this at the bottom of your lens barrel near the camera body or at the end on the rim around the lens glass itself. There should be a Ø symbol with a number next to it. This is your lens diameter. If it says Ø 52 then this filter will fit your lens. If not then you need to buy a filter with the appropriate diameter. I can confirm that this fits perfectly on the Nikon D40 kit lens (the 18-55mm).
Also be careful with the screw thread - it can be very easy not to attach it properly so it slides around or is crooked. It can take a few tries to get it on properly, but I expect this is the case with all screw-in filters.
All in all this is a good investment. Scratching this £13 protector rather than your £75+ lens means it pretty much pays for itself should the worst happen!