Pros: Expert terrain, vertical (for area), ticket price
Cons: low snowmaking ability, slow/old lifts, minimal infrastructure
Blue Knob is probably the best mid-Atlantic ski area when the conditions are right. It has some of the most challenging terrain in the area, 1000ft vertical, usually doesn't get too crowded and is cheaper most of the other mid-Atlantic ski areas as well. There are a good number of long trails for experts and intermediates.
So why isn't Blue Knob five stars? Well the caveat when the conditions are right is the main reason that it only gets a four instead of a five. Blue Knob has a reputation for being icy and there are a number of days in the season when the best terrain isn't open due to lack of snow. It's hard to rely on mother nature to provide snow in the mid-Atlantic and Blue Knob doesn't have the snow making abilities of other mid-Atlantic resorts. Many area resorts will be fully open, including ones that get much less snow, while Blue Knob has the expert portion of the mountain closed due to lack of snow.
I personally don't mind the slow lifts, though I certainly wouldn't complain if they were upgraded either. There also isn't much at Blue Knob accept the slopes. If you are going to Blue Knob, you are there to ski, not to hang out at the lodge. And don't expect to party either. Blue Knob is fairly isolated and there isn't much in the area.
Still, if I know conditions will be good, then Blue Knob is worth the drive for me even though there are many area resorts that are closer to where I live. The terrain is just that much better, when it is open, than what the ski areas closer to DC have to offer.