I've twice had them and have to say that they are extremely narrow, extremely hard, and don't have as much fore-and-aft adjustability as many European saddles. There is both a padded and an unpadded version, but the padding doesn't have much effect. I ride an SLR, which is pretty narrow, and can ride these for short events but if I ride 30 miles in an evening on a track training session, I really am sore the next day.
Note that these come in two frame widths. They usually come with a 30 mm width (which helps make them extra narrow) but require a specially-sized seatpost to match. You can't mount the 30 mm versions on a standard European or American seatpost. The standard in the rest of the world is 44 mm. There are Kashimax saddles in this width, but they are somewhat wider as well in the midsection to accommodate this wider frame.
If the saddle feels bad riding down your street, try it on the track with centrifugal forces pushing you into the saddle. It's easy to push a lot of saddles right down into the rails when you are taking a banking at high speed, which is why track racing tends to use more big clunky old saddles than the road (the Rolls and Turbomatic are popular favorites).