The mirror hangs on a suction pad and hook. This works well. Rinsing under the shower stops it steaming up for a while. You can easily take it travelling. In practice in my experience I can't always see well enough to complete a good shave in the shower and I have to finish using another mirror. Also it makes you take longer in the shower so you probably use more water and energy.
Have used it a few times now and would say that It isn't really fog free. Given the ~£12 price range I'd have expected better.
I'd say your better off picking up a cheaper travel mirror in boots 1/3 of the price which would have the same effect as this mirror.