Steven Sande at TUAW reviews the Logitech Ultrathin Keyboard Cover:

Combining the protection of Apple’s Smart Cover and the typing ease of the Apple Wireless Keyboard into a wafer-thin cover is a great idea, and Logitech’s execution of the concept is essentially perfect. Without a doubt, this is the best iPad Bluetooth keyboard on the market at this time.

If I were going to get an iPad-keyboard-case-type-thing, Logitech’s Ultrathin Keyboard Cover is probably what I’d spring for. I don’t want one of those keyboard-cases that permanently attached to the iPad because I use my iPad without a Bluetooth keyboard far more than I use it with one.

But, I use the Origami Workstation from Incase along with my Apple Bluetooth keyboard and it is all just great.

Though, one thing I like about the Logitech Ultrathin is that it has specialized iPad keys (like one to go to the Home screen, one to activate Spotlight search, etc.). The AmazonBasics iPad keyboard has these buttons as well, and in my time of trying it out I found that I used the specialized keys quite regularly.

TUAW’s Review of the Logitech Ultrathin Keyboard Cover for iPad