When I did do the Zone diet (very similar to South beach but more portion controlled), it worked really well. BUT it's kind of complicated. You need to measure things to get the full benefit. Plus you need to monitor yourself to see that your Carb/Protein/Fat breakdown is adequate. Some people need more carbs to protein, and some less. I was having trouble finding the right balance. But once you get into it it works really well. My problem is it's not something I've been able to get into long term, and that's not the best thing for weight loss.
I recommend getting one of Barry Sears books. They really explain the science behind it.
As far as food, I don't think it was hard to prepare (meats, veggies, salads, berries, etc), but it did take a lot of planning.