My wife and I rode Special K a couple of days ago.  FYI, the loop we did was Sulphur Springs to Pneuma to the road [exit at Race of Spades] and up to Special K, then on to Tom Snow and then Ridgeback.

Special K starts off with a couple of curvy downhill turns, and then goes straight down for a while, so drop your seat.  The first 200m or so is easily the most challenging part of the trail, as it is loose and eroding.  Once you get past that, the trail continues down, down, down, crossing a drainage on nice, solid bridges that you can ride across easily.  The entries to said bridges are steep, but you already have your seat down, right?

Once you are over the last bridge [6' wide], the trail becomes full XC.  There are a couple of wee stunts here and there, but the better line is to bypass them, and it looks like almost everyone is.  The trail is not bench cut in most spots, but that is only an issue when riding through a couple of meadows where the tread width is about 4" and has a 1" root every couple feet. 

If you have been on Special K in 2009 or earlier, you may recall that the trail took a sharp dive down a rutted creekbed and wound through a swamp before getting to Tom Snow.  Thankfully, the trail was totally re-routed last fall, and follows the ridge much further, exiting onto Tom Snow about 500m north of the Ranger Creek Crossing.  MUCH better.

All in all, I'd recommend Special K for an after-work ride, especially if you don't have the time to ride Moosepackers and Ridgeback.