I bought one of these Logitech K800 Wireless Keyboards a couple of weeks ago, so far I am very pleased.
The only thing I didn't like is the small left shift key, but I'm getting used to it now.
I really like this keyboard style, it feels very comfortable to type on for long periods.
Here's some of the features I really like:

PerfectStroke™ key systemThe PerfectStroke key system distributes typing force evenly across key surfaces, making every keystroke comfortable, fluid, and whisper-quiet.

Hand proximity detection
Sensors detect your hands as they approach the keyboard to turn the backlight on and off.

Logitech® Incurve keys™
Durable concave keys position your fingers properly, and their softly rounded edges invite your fingertips to glide from key to key, hour after hour

Fast, easy recharging
You simply plug in the universal micro-USB cable for three to six hours for up to 10 days of battery life.* You can even type while it’s recharging.

Logitech® Unifying receiver
The tiny receiver stays in your laptop. Plus, you can easily add a compatible wireless mouse or keyboard—without the hassle of multiple USB receivers.

I haven't had to charge it since I unpacked it either, unlike the Logitech MX5500 Bluetooth Keyboard & Mouse set it replaces. Now to choose a mouse, preferably something that can go on the Unifying Receiver.

I would definitely recommend it