The entire trail is within Bottomless Lakes State Park, so there is a fee. You can pay it and obtain a vehicle ticket at the park's Visitor Center, or at any other self-pay kiosk within the park.
Skidmarks Trails is a special kind of trail that manages to be flowy despite being relatively slow--because you're endlessly changing direction through well-designed corners.
The trail includes a few rock and timber bridges, but they are all well-designed, solid, and easily traversed.
Despite being a short ride at about three miles in length, you'll want to ride it again and again in both directions. You'll be riding some bumpy sections, over a few 5" obstacles, and sweeping through tacky s-turns at the bottom of the coulee.
Most importantly, though, you'll be sawing that handlebar back and forth all the time with a smile on your face. And even though it's entirely built in and around a coulee, there are none of the long, steep climbs or descents you might expect in that environment, so it rates as 'Easy/Intermediate'.
Kids might even enjoy it--albeit at a slower rate and with some occasional hike-a-bike.
According to the park's brochure, the trail adheres to IMBA guidelines and was constructed by local organizations including the New Mexico Military Institute, the New Mexico Youth Challenge Academy, and Boy Scout Troop 19 under the direction of Park Ranger Travis Reardon. All funding was provided by the Friends of Bottomless Lakes State Park.