My wife and I booked the bus tour as a package with the movie and the cyclorama, which were both outstanding. We had the misfortune of getting on the bus at the end of the boarding queue, which meant we had to sit in the back row, which meant we sat right over the bus's engine.
From the beginning, people had some difficulty hearing the guide and asked him to speak up. Either everyone else heard him just fine after a short while, or the engine noise kept us from hearing him. Whatever the case, we couldn't hear very well, and what we could hear seemed to consist in large part of him cracking jokes.
We stopped a few times and got out of the bus, which improved the auditory situation somewhat, but couldn't help with the two young boys seated near us who seemed to want nothing more than to bop each other over the head with empty plastic water bottles. From time to time they tried to balance the bottles on top of their grandfather's head, who tolerated their tomfoolery.
I am something of a history buff and already knew a fair amount about the battle. Nevertheless, I learned a few things and believe I could have learned more, given a better learning environment. You can hire a guide for a guided auto tour, which I believe would be ideal in case you want to get really up close and personal with the battlefield area and the events of the battle. If you choose to ride the bus instead, get a seat near the front of the bus, preferably a bus devoid of young boys...