If you adopt SB as a lifestyle and not a diet it is not terrible.
SB starts off with a 2 week induction plan which is quite strict and then introduces carbs back slowly for long term maintenance..the problem is that many people are desperate to lose weight, do not follow the program, and try to continue the 'crash' induction long-term which always backfires.
If you follow it properly, to a T, and follow the proper meal plans (which are outlined in the book), then no, it's quite fine.
Some good info:
https://www.3fatchicks.com/forum/south-beach-diet-110
https://kalynskitchen.blogspot.com/
But you need to follow it properly and not do what most people do - which is try their own version that ends up in disaster
Good luck. I have not done it myself but I have read the book inside & out, have done many of the recipes. I do not follow a "diet", I do my own calorie counting. It's a very reasonable plan. And anyone who knows me here, knows I hate fad diets lol so I wouldn't recommend it just for the hell of it.