I've done South Beach Diet twice and got to my goal weight both times.
The first time I had teenagers at home, my DH was working long hours and wasn't interested in fixing family meals
and I was working full time as a k teacher and part time teaching adult ed courses. I had way more ambition than time and we were used to eating snack bars/junk food regularly anyway, so I ate a lot of processed foods as part of my SBD plan, including the SBD snack bars and frozen meals. I don't remember struggling more with cravings when I ate that way, but I did eat a lot of SF jello, pudding, candies and sodas. I know it was a lot more expensive - but I was okay with that. I lost my weight and kept it off without much struggle.
I slowly gained the weight back (+ some) when I started taking prednisone and other medications a year or so later, and when I got up over 200 lbs again I got fed up and came back to South Beach. My DH is retired, our kids are grown and living on their own and I only work one job, so I've had more time to think about what kind of foods I want to eat. This time my focus has been less on losing weight and more on feeling better and being healthful so I avoid the snack bars, frozen meals, etc and eat more vegetables, fruits and nuts than I ever have. I spend more time planning and preparing meals and snacks now, but the longer I eat this way the easier and quicker it gets.
For people who have the time and the desire to stick to less processed foods, I heartily recommend it. I feel so much better eating this way and it's really much easier and more economical than I realized. But for those who don't or can't, the snack bars and meals are a convenient option.