iPad's touch keyboard covers more than half its screen, obscuring most of what you compose. Bluetooth keyboards from Logitech and iLuv are designed to free up iPad screen real estate and make it easier to compose text. I've had a chance to play with them and here are my impressions.
iLuv's keys are packed tightly against each other. As such, it is nearly impossible to type without accidentally hitting an adjacent key, which leads to a multitude of annoying typos. As with all iPad keyboards, you get handy up/down/left/right cursor keys minimizing your having to touch the screen to move the cursor around, and a row of iPad-specific function keys – Home, search, photo slideshow, video/music transport and volume controls.