All I can say is enjoy it. IMO it's one of the best trail networks in the state. Well marked trails (maps available at trailhead), well maintained trails, good variety of terrain, being 'out-there' factor, trail routing/layout allows for a ride of any length - from 2 to 25 miles.
For solid XC riding - little bit of everything, I'd recommend the following trails (they pretty much all flow into each other): Upper Glen, Lower Glen, Swamp Cut, Yellow Jacket, Goat Dance (I like to ride this loop trail counterclockwise), Fox Hole Run, Upper Hermosa, Hermosa, Lower Hermosa, Dead Turkey, Warm-Up.
The trails up on the mound (identify-able by the contour lines on the map) are fun, but are generally slow going rocky technical trails. Give them a shot if you're into that stuff. Trails like: Toad Road, North Face, Cliffhanger, Switchback, Porky Point.
The only trail that really is affected by rain in the summer is Snodgrass - it has a lot of low lying areas = mud year round.
Here's a couple teaser pics from a ride in early June this year.
Goat Dance - before the climbing sections
Goat Dance - about 1/2 way up
Upper Hermosa (I think that's where I was)
Toad Road (does anyone know if this section has a name?
Toad Road (just around the corner from the pic above)
View from atop the mound - to another point you can bike to (watch the ledges!!!)
Another scenic vista - I believe that's Bruce Mound in the distance (this is about as good as it gets in WI for 'mountains'
North Face - decent rocky chute just after this crest
Cliffhanger