Yes I have been there. Their exibits are broken up into different time periods. 3 or 4 of them are open, starting with the modern day and working back. They are going to open up a couple more starting around the civil war time period and before. They have what is called the Last 100 Yards exibit first which depicts the Infantry in battle over the years.
They also have an IMAX theater, gift shop and a restaurant there as well. I've heard the restaurant is good, but I havn't eaten there. I have taken several friends and family members there and would definately recommend it.