I did it all in 2 days. The trail system has a lower and upper section. I did all four bottom trails the first day, starting with Deep Step, going counter clockwise, and the next day, went out Deep Step to the connector to Big Rock and Tower. It was awesome. It is not hard at all, but pure fun. The miles seem like nothing. Best sections are definitely Deep Step and Tower, but there were parts of Great Wall that were fun as well.
I would actually take 3 days if I were you, and do as much as you can at a moderate pace the first two days. It's easy to get going too fast on these super-flowy unfamiliar trails. It is not hard, but just unfamiliar at speed. Then after getting used to it, take the last day to redo your favorite route at an even faster pace!
Watch out for people coming the other direction and sneaky doubles, and curves/chicanes.