I purchased this receiver thinking it was the official receiver made by Microsoft. Once I received the actual item, it became apparent that it was not. The main thing to look out for is the lack of the "Microsoft" logo on the item itself and the packaging. If you intend to buy the official receiver, make sure "Microsoft" is clearly displayed on the front.
In addition, the item comes with no user instructions and a driver disc that doesn't work under Windows 7. It certainly doesn't work out of the box as an official Microsoft product would, and requires you to manually set the driver, which takes some tech knowledge.
Other than that, once you do get it working it doesn't seem to have any major issues. All the inputs register fine and it has a reasonable range. Just make sure you're fine with buying a knockoff rather than the official product.