It's good for you, but it is high in calories. Complex carbohydrates do not cause the insulin spike. The previous kinds, on the molecular level, are mono- and disaccharides. That means, they are composed of one or two molecules of sugar. It takes little energy to release them into your blood stream and cause insulin to spike.
Complex carbohydrates are polysaccharides, which means they are chains of dozens of sugars.
It takes a lot of energy to break them down, so they don't get all released into your system at once, and cause the insulin spike. These do not cause insulin spikes. Here is a table from the same Men's Health article that I quoted earlier. Now this doesn't mean knock yourself out on chocolate and peanuts. It does make for a better snack, though.