Just know that this is a personal transaction between two individuals and you book with this person and pay this person. It involves a good deal of trust. You will not be able to call and confirm your reservation, so make sure you deal with someone you are comfortable with. You will not be dealing with Disney.
Most never have any problems but problems can arise. You might want to read some of the comments on the DVC forums.
The DVC member you book with controls your reservation, etc.