The main trails are mostly good these days. Some areas are a little washed out, but all ridable. Purple could really use some love as the off-camber bits are a little sketchy. Still ridable, just be careful to keep your traction, otherwise it's you+bike+swamp.
The unofficial trails across Springdale are nearly impassable from the Springdale entrance after the most recent tropical storm blew through here. I counted at least 7 down trees and while I managed to hike my bike and self back there, it's a really bad time. If you can find access from another side, I'd recommend that. The trail clears up as you get closer to back area, and the ttf's and whatnot are pretty much open if you can find a way back there.