I've been using one for a few months now after having had a Spoon for about a
year. As theotherjonv said, the shape is the same as the Spoon but the Knife is firmer and less padded but still comfortable.
Put one on my main bike just after xmas, so not long ago. So far so good though. Build quality seems ok, shape is good – if anything, it's a bit too padded for me, but maybe it'll pack down a bit.Weight is excellent as are the looks. For the money, it seems alright.
I just picked up a ti knife from winstanleys for just over £30 which is a proper bargain. The spoon fits me very well but I was looking for a slightly lighter saddle so went for the knife. Not had a long ride on it yet but a quick 3 hour blast without padded shorts and no dramas or sore bits