Despite the fact that I had no one to ride with (was hoping to find some other ladies there but didn't see any), I had a great time. With the island being so small, I ran into the guys several times, and I'd ride with them for a bit and then either not be able to keep up or take a turn when they went on a technical trail.
The island is a nice mix of very simple beginner trails and twisty, turny, more technical trails for advanced riders. You aren't going to practice your climbing or downhill skills here, but you can certainly work on turns and choosing good lines on single track trails laced with random tree trunks, old manufacturing building debris, and large rocks.
After a couple of hours of riding, I'd had enough, so I did a bit of trail running on the island while I waited for the guys to finish. I'd love to go back and do more running there--I think it is even more suited to running with its small size and technical yet not-to-hilly trails.