That depends on if you are financing with Disney. If you are financing with Disney, you will basically have to fill out a financial application form and then sign a lot of mortgage type papers, you would want to read them and make sure all the figures are right. You will have to sign the actual mortgage doc in front of a Notary. There are also several documents asking you to sign and acknowlege you received things such as the guidebook.
It really depends on how much you know about DVC as to how much you will have to read of the member guidebook. I have been lurking around DVC and these boards for a couple of years so there really wasn't too much new information for me in the guide book so it went pretty quickly, but if your new to it all you would want to read it more thouroghly before making your final decision and signing everything.
DVC makes it fairly easy, you basically have to sign in all boxes with Mickey ears and date in any box with palm trees. They then give you a pre-paid Fed-ex envelope to send everything back in.