The Good: The MK2 is the updated version of the Micro Knobby. The biggest change is the center strip of tread (see the pic? ^^^). The knobs in the center are now inverted - this fixes the durability issue the old ones had.
The Bad: Cornering traction in loose dirt, but then again it's supposed to be a fast rolling and nearly slick tire. Outer knobs have potential to wear quickly given their small size.