Good.
I've used it many times to alleviate the pressure points that develop if you have a bony butt like mine. The trick is not to over-inflate it. The correct inflation is such that your butt is *just* off the seat, otherwise it feels like you're sitting on a balloon. It does add extra seat height, so something to think about if your bike is tall. Also, if you like moving around on the seat when you're riding the twisties, then you might want to remove it from the bike for better feel, and then re-install for the superslab, it's fairly easy to do with the straps attached to the AirHawk.
There are a couple of sizes and shapes, make sure you get one that fits properly on your bike.