if you're using a sinar, it really works well. When I was looking for one they were nowhere to be found--for several months--so I broke down and bought the Luland clone. Of course a week after I ordered it, a genuine one popped up on KEH...sigh. Anyway, the Luland built one is very well made, so I'm not sad. What I really like is that it doesn't add nearly as much height as other 3-way heads or even ball heads. The main limitation is while tilt in one direction (up or down depending on which direction you mount the camera) tilt in the other direction is probably limited to 15-20 degrees.thats easy enough to deal with by just mounting the right direction if you're going to use any extreme dutch angles.
Its not too useful on most other cameras because it relies on the Sinar's ability to rotate the rail inside of the tripod clamp in order to gain the third axis of rotation. Mine is permanently mounted on a Gitzo G345 tripod.
EDIT: here is the clone version I bought. in use it seem every bit as good as other Sinar gear I own, and the design is almost idential (different tilt knob, but still says Sinar on the side)
Tilt Locking Handle:Placing by any angle after locking without affecting the whole machine operation. Scale Mark : Laser Engrave,Clear Writing. Horizontal Rotating Locking Button:Humanized-design Conner, Compatible Operation.
www.ebay.com