Pros:
Less ground pressure, the machine will do less damage to turf than a wheeled skid steer. It also allows the machinme to work in muddy conditions where the skid steer would be sidelined.
These machines are more stable than a skid steer on uneven ground, and usually have a higher tipping rate than the same sized skid steer.
Cons:
Cost. Quite a bit more expensive than skid steers, plus replacement tracks are expensive too.
I have no first hand experience on the tracked machines, but have talked to colleagues who own them, they love them. These were the Cat machines though, I have no specifics on the ASV model.