This is a fantastic product that works exactly as it should, and depending on your circumstances (i.e. whether you need your 360 to be wireless) this will serve you well. It gets four stars rather than five because it is too expensive. That's not to say it's not worth a purchase, but there are cheaper alternatives out there. But as for the rest of this, I'm going to address some general concerns that have cropped up in these reviews. Hopefully they will be some help to people.
1) HOW TO INSTALL IT: The wireless adapter itself literally clicks on to the back of the console. There is a space for it already there. The cable is a straightforward USB connection that also just slots in to the back of the 360 when the router is in place. It's incredibly straightforward and will take a matter of seconds. As for installation, the adapter doesn't need installing as such. Your 360 will automatically detect it and detect wireless networks. All you need to do is to go to Edit Network settings on the Dashboard, scroll to the third segment of the screen (the bottom segment), and choose your wireless network from the list (if there's more than one on there). Then insert your WEP/WPA key (if you only have WEP I'd recommend changing it to WPA, it's more secure, but that's beside the point). It'll then ask you to test your connection, which you should do, and everything should come back completed. A green light will then pop up on the back of the adapter and you're good to go. The whole process should only take five to ten minutes.
2) I'VE DONE ALL THAT, BUT I STILL CAN'T CONNECT TO XBOX LIVE: Like with any product, there are faulty adapters out there. However, chances are the issue is not with the adapter. Double check that your WEP/WPA key has been entered correctly, and ensure that you have at least a half decent signal. Though problems with this product are rare, there are many possible issues that could arise in any given situation. No room to address them all here, so I'd suggest Googling them. Nearly all have solutions.
3) CHEAPER ALTERNATIVES: There are cheaper alternatives to this if you want to play online wirelessly with your 360. Apparently you can use the original Xbox adapter in the same way, which you should be able to find much cheaper. I haven't confirmed that myself though (and the original adapter will not look as good as the sleek 360 one). You can bridge the connection through another computer or laptop as well. I'm not going to go into detail about doing that here because I don't have the room, but it's nice to be aware of the alternatives.
4) BT HOMEHUB COMPATIBILITY: This product works fine with BT Home Hubs. I'm using it with one at the moment, and indeed have been doing for a while. I've used it with a variety of routers (Netgear and Belkin included) and never experiences problems.
5) WIRED VS WIRELESS: If you can connect your 360 with a wire without inconveniencing yourself, then wired is always better than wireless. Only go for a wireless connection if a wired connection is not possible or practical.
6) DO I NEED A WIRELESS ROUTER? Yes, you do. The wireless adapter is just like one you would plug into a lap top (or like the ones that most laptops have built in nowadays). You still need an internet connection in your house, with a wireless router connected to the phone line to use it.
7) IF MY 360 OVERHEATS, WILL THE ADAPTER MELT? No, it won't. Obviously there are faulty adapters out there, but most of the time issues with the 360 overheating are just issues with the 360, and are not caused by the adapter.
Right, there we go. I think that addresses most of the concerns that I've read about in the reviews. Happy (wireless) gaming everyone.