I bought this when it was only £19 so I thought it worth the risk. I already had XBOX live connected via a cable into the next room which was not ideal, although NAT settings cause an error to do with open NAT, but this did not seem to cause a problem in real game play. (According to my son - I don't actually use it)
Having read many frustrated reviews on how difficult it is to set up I read up on this before starting. I strongly recommend you look at Youtube "Mad Catz Wireless N Adapter for Xbox 360 Review & Set-up (Part 1)" by mediaassault (thankyou!) - it continues with part two, and gives a good idea of what you have to do.
When I inserted the CD it wanted to autorun the install program, but I declined this and instead looked at the contents of the CD. I first looked at the manual which came on the CD and set up my network settings on the laptop to 10.10.10.101, with subnet mask 255.255.255.0 Dont forget to close the settings box to save the changes.
I attached the network cable from the laptop to the Mad Catz box and turned it on.
I then opened Internet explorer (not Firefox as some people have had problems with this) and typed in 10.10.10.254 (this is the address of the mad catz adaptor) and expected to see the onscreen dialogue as shown in the youtube video. The mad catz adaptor address was not recognised.
I next ejected the CD and re-inserted it, this time I ran the install program and it recognised the adaptor. I followed the onscreen instructions and also mediaassaults step by step guide. One difference for me was security settings, my old belkin router uses WEP and I selected "open" as the setting, and entered WEP key.
When I connected the Mad Catz box to the XBOX it worked fine. The open NAT error was still there but the XBOX still connected.
My son runs COD and HALO reach online and has reported no difference in its performance compared to the wired arrangement. Saints Row 2 did have some lag so I can't say that its 100% successful. I am only running a "G" router and that may be an issue. I have since fixed the open NAT problem, but we haven't run Saints Row 2 since to check.
All in all I think its a working product, but I am confident and capable with IT and networks so it may not suit everyone. I hope this helps if you do buy one.