When looking for PDA accessories, I really like products with a true "geek" factor.  The Logitech KeyCase Keyboard is definitely one of those products.  At first look, it reminds me of the velcro, waterproof wallet I had as a kid.  This is a cloth keyboard with integrated circuitry  that "feels" where on the keyboard you are striking.  Because it's made of cloth, it easily wraps around your PDA when not being used and still fits nicely in your pocket.

The use of the keyboard is a little less impressive to me.  You really need to use it on a hard surface for maximum stability.  The keyboard and the buttons are slightly smaller than most portable keyboards, causing you to really have to pay attention where you have your fingers.  For me, the biggest issue is the lack of tactile response when typing, meaning that you don't get the "clicking feel" of a regular keyboard.  This lack of feel will probably not make this the keyboard of choice for regular typists.

Overall this is a pretty neat accessory.  While it may not appeal to someone who types quite a bit, this is a great product for typing the occasional email or memo.  My recommendation is to find a "demo" at the local electronics store and try for yourself.