Say whatever else you want about them, Microsoft has always made amazing peripherals hardware. I got their Microsoft Wireless Desktop 900 keyboard/mouse set, which is much the same as the Wireless Keyboard 850 in a kb/mouse bundle. It's no exception - reasonable price, great quality, does exactly what it says with no nonsense and stray LEDs. The keyboard is really flat and convenient.
Unfortunately they took the minimalism a bit too far. The keyboard has no power switch.