One of the "cardinal rules" for home acquisition is, regardless of whether or not it's a resale or new construction is the importance of having your own representation.
In many cases an agent will be able to share with you the sales history, price incentives, and promotions offered by the builder as well as help you obtain the best possible price for your new home.
Try this test....walk in any builder's sales office and indicate that you are working with an agent. They will likely inform you that you will not require their services because they will take care of your needs. The reality is that you may be viewed a more vulnerable without representation.
Most agents will assist you in monitoring to homes progress by visiting the site, taking photos, and acting as the liason between you and the builder. A good agent will be there for you from beginning to end and most certainly help protect your interests.
Sure you can go it alone but the chances of having unresolved difficulties become much greater.