I have been over a couple of times now and there is plenty of good riding and loads of trails. I have a mate who lives there though so he was "guiding".
I can try to dig out a few gpx's of routes we rode if you are interested?
There were so many trails going off in all directions but they aren't always marked very obviously. A coloured dot painted on a tree was often all that marked the trail head. My mate did say though that there has been some work done of late, to try to link up a lot of the small trails into a proper network with some more signage but I'm not sure how much has been done.
Here's a video of one of our trips that shows the sort of riding.
https://vimeo.com/62724865
I should have been going across for the Manx100 at the end of July but I suspect my knee problem has put pay to that.
