The drive we took to the site from the east was fairly long and mostly isolated. It was very pretty in places, and there were many old abandoned buildings along the way, if you have an interest in those. We left toward the west and found it to be more farm land than the other direction. The mound park charges $8 per car, and you are expected to pay even if the museum and gift shop are closed, so bring cash. There are bathroom facilities available even when the center is closed.
The walk to the mound from the car is an easy one, and the trail around it is very near the mound, crossing it in one place. You are not supposed to walk on the mound for obvious reasons, except on the crossing. I'm not in great shape for walking, and I had little problem with the trail. It is a fascinating thing, and it was nice to see it first hand. There is an overlook, but the area below is so overgrown that you can't see anything beyond. If you enjoy hiking on unpaved trails there seemed to be several there as well. There is also at least one burial mound on the site near the parking lot.
One caution: The county where the park is located does not spray for mosquitos. While we were there I was attacked quite a lot by mosquitos on my exposed skin. The other areas of Ohio where we went on this trip did not have this problem. Apparently the site managers are aware that there is standing water in the area, but believe the area wildlife is fed by the mosquitos, so they won't spray for them. Be sure to take precautions before venturing outside at this site.
Scott D. on Ohio Brush Creek Hiking Trail (Serpent Mound)
The "X" factor is seeing The Serpent Mound, and the man in the office knows a lot. I didn't see any aliens, but the trail was a short trail, and looked similar to anything else in southern Ohio. The mound is the best part.