This little box is a life saver. I got it so that I could stream HD movies to my PS3 over wifi. The built in wireless G connection simply can't handle the bandwidth, so I upgraded my router to wireless N. This box is used to upgrade my PS3 to wireless N so that it can actually receive a stream at up to 300mbps. Now in reality, due to interference and other factors, you'll probably only get around 80-120mbps of actual speed, but this is sufficient for HD - especially since the ethernet port is limited to 100mbps anyway.
It was easy to set up with the install disk, and has worked flawlessly since I installed. Haven't needed to reboot it once. Overall very pleased.
Btw, the main advantage to this product is that it has 4 ethernet ports and is easy to setup (oh, and it looks great). There are slightly cheaper alternatives, such as the Edimax wireless N access point if you just need one ethernet port (found here: Edimax EW-7416APN Wireless 802.11n Access Point ¿ Range extender
), but it's a bit more difficult to set up due to its poor instructions (I have one of these as well).