I would say yes. I'm not necessarily dieting, but I do count calories, and at 290 calories this is the perfect amount for me for breakfast -- any less and I would get hungry before lunch, any more and it would be more than I really need.
It really depends on your calorie intake (if you're counting calories). It's 290 so that's about as much as a breakfast (plus I'd recommend adding a fruit). It also, unfortunately, has a lot of sugars. There's no REAL counting for sugars in a diet but the recommended amount is anywhere between 30g - 45g /day. So i would simply recommend this product as a breakfast every other day or so.