The park was designed by Huna Designs. The ramps and spines seemed to be all metal with some sort of a smooth surface (I thought at the time that it might be fiberglass). Huna Desgins' website calls the surface Skatelite Pro™. It seems to be the surface of choice for the likes of Tony Hawk, Matt Hoffman, and Dave Mirra. (The only reason I recognize these names is because my boys watched the X Games a few months ago.)
There were about 10 - 12 kids there using the park (they must have had the day off from school just like us), including 3 or 4 girls. Their ages ranged from about 10 years to 14 years. There was a mixture of roller blades and bikes using the park. I did not see anyone on a skate board.
It seemed that there might not have been quite enough room for the bikes, because they would start outside the fence, ride down the path leading to the skate park, ride through the gate, and into the park to get up enough speed to do the tricks inside. Though that didn't seem to discourage them.