I use ACC all the time, probably too much, but I love it. Yes it has a few annoying quirks such as leaving too much space between the car in front sometimes, occasionally forgets to break and slams on a bit strong, pick up is a little slow in ECO mode, but on the whole it's a great system especially for lazy driving and in super heavy traffic. Coupled with DSG the car practically drives its self.
Still can't believe its standard across the entire Golf range.