If you think of a Skyline as what its supposed to be... ie a sporty passenger car, then HICAS is awesome. If you take a corner too fast it kicks in and helps you keep the car in control and back on line.
If you're a fully sick drifter or die hard trackday warrior, then HICAS is like going on a date with a hot chick and having your mom run upto your car to give you a scarf so you don't catch a cold... ie... nice thought, but totally useless. You want to control your car one way, and HICAS wants to help so it makes your car go the other way.