I went there yesterday for my first ride of the season and my first at Sourlands. The place is brutal tech. I wish i went the clockwise direction, which i should have known if i paid attention to the elevation on the map.
The big loop is one of the most technical i've seen in NJ. There are parts that remind of Blue Mountain, and the easiest stuff reminded me of the most technical parts of Chimney Rock. I had to do a lot of walking on my way up, but it was exciting to see some terrain that i could advance to some day.
Definitely a good place to learn technical terrain, i won't be seen there without leg and arm protection.