Smilkameen trail in good shape, hard packed with probably about a dozen trees down.
Windy Joe trail in good shape, hard packed and a little icy down low, softer snow up top. Probably about 2 dozen trees down.
One of the resort staff told us that they had a wind storm that took down a bunch of trees a couple of weeks ago (same time that Chilliwack and Hope had the freezing rain).
Edit: If you go and have the time, a medium size hand saw could take out some of the blowdown, but most will take a chainsaw.
And yes, mountain biking is allowed on some of the trails in Manning.
http://www.env.gov.bc.ca/bcparks/explore/parkpgs/ecmanning/#Cycling