Isn't it all sketchy old-school fall-line singletrack?
Not anymore.
Haven't they wrecked all the cool old-school singletrack with their machines and "flow" trails?
No, there's still some around, but you need to know where to look.
What's up with the locked gates? Are the trails closed?
The gates being locked doesn't mean much. There have been some problems with vandalism and theft in the past, so if no one is around, they are often locked. You are welcome to park outside and ride from there. Or park at Pleasant View and ride from there. Or park at your house and ride from there; Middleton's bike path network makes it easy from alot of different places.
Isn't it a really exclusive private club?
No, it is actually a 501(c)(3) corporation whose stated mission is to develop and promote youth sports in the Madison area. It is private land, and without taxpayer support and the legal protection of being a public park, there needs to be a way to cover expenses and liability, so you need to be a member. $25 individual / $50 family for a summer membership is pretty reasonable. And Blackhawk has invested quite a bit in the last few years in trail improvements, so it easy to see where the money goes.
Is it worth joining?
If you live on the far east side and might only make it over once or twice, maybe not, but even then, it is still cheaper than most downhill ski lift tickets. If you live on the west side and can make it there once or twice a month, the Pleasant View/Blackhawk combination is well on its way to rivaling any other local trail systems in terms of amount and quality of trail. So, yes.