The product is really great, its actually genuine Apple. The build quality, finish and fixings are brilliant. It arrived promptly and packaged well with some other items.
A serious word of warning, unless you are a serious and skilled enthusiast then do not attempt this procedure. This is really not for the faint hearted, with a good youtube video you should be on your way though.
Really contemplate whether this is necessary, I cannot get my sim eject tray to work and the home button is now a bit dodgy. I feel I've compromised the apple build quality significantly.
If you do decide to do this, organise your screws!! They aren't all the same! If you really have to do this then purchase all the other broken parts and do it in one go, I wouldn't recommend taking these apart often.
One other word is that this doesn't include things like the microphone and speaker 'grills' nor does it include the iPhone camera silver rim (Visible from the rear of your phone). You may find you need some adhesive and possibly easily usable double sided tape, doesn't have to be strong just very thin. These guys also sell a case opening kit which was brilliant, you can't do the job without it.
As far as this product goes it's really high quality, only £14 and free shipping for a Genuine apple product, many websites charge £40+.