Not much to say. The product is exactly what it says. A genuine copy of Windows 7 home edition premium.
Very simple and easy to use.
Being an OEM copy this means that you don't get the CD on a pretty box, also you don't get an instruction manual but 1) you really don't need one, and 2) just write "windows 7 manual pdf" on Google and you'r done.
Another (irrelevant) problem of buying an OEM copy is that you don't have access to the free support services from Microsoft.
Finally, as OEM, this software will be tied to the computer of its first install. In other words, this mean that you can change all the hardware on your PC except for the motherboard. Once you change your motherboard you wont be able to reinstall. Some say that if you make a phone call to Microsoft, on some cases, they'll give you a new key but keep in mind that might not happen.
But keep in mind also that, as we stand now, buy buying an OEM copy you will be saving around 100£+. So, basically, even if anything goes horribly wrong with your PC, you can buy yourself another OEM copy and still save money.
Unless you are completely unfamiliar with PCs, I advise you 100% on getting one OEM copy of windows. The install is pretty straight forward and you have YouTube videos (and the whole internet) that will clarify most of your doubts batter than any support line.
As for the product it self. In my opinion, Win7 is the best system since Windows XP. So go for it.