Family Friendly: Trail is suitable for all skill levels.
A 25-minute drive from downtown Charleston, the trailhead has ample parking and two Porto-Johns. No running water that I saw.
The Red Loop is the main trail and is approximately 14 miles long. It is very well-marked with large red blazes on trees all along the way. There are several small loops that leave and return to the main trail that are marked in yellow. Around the 10-mile mark, there is a ~three-mile add on for the Foster Creek Loop
marked in orange.
The turns are smooth and there are no technical features on the trail. If you want work, you'll need to pedal harder as the terrain will not provide it.
The trail is open year round, and and when I rode it, it was in very good shape with no ruts or erosion. I have seen several comments about roots; in my opinion it is hardly worth mentioning as for the most part they are sparse. If you ride a full suspension bike, you'll not notice them.
The Foster Creek Loop
does have more roots and could be annoying on a hard tail.
Marrington is a great way to see the low country; a beautiful area and while I was riding very few people on the trail.