A community representative can offer a great deal of insight on the overall plans for the development but at the end of the day, have the developer's (or builder's) best interests at heart when it comes to negotiations.
Know that the information provided is designed to demonstrate the MOST value possible, thus impacting your opinion in such a way as to make the homes seem more valuable than they actually may be. Your representative should do the exact opposite so that you have a full understanding of values. Likewise, a buyer's rep may also know other options which may be better suited for your needs that the community rep will have no interest in making you aware of.
We wrote a post about dealing with builders here -