I use Atkins Shakes during the day, and I know that per the calories, fat & fiber that my shakes are 3 points per shake. Slimfast shakes are much higher in calories & carbs than the Atkins shakes, too.
I have some of the Strawberry and the Milk Chocolate ones... running them through the points calculator on the WW website said they were 4 points each.
I guess it's not bad if you can stick to just THAT for a meal... or maybe paired with some 0 point veggies?