I have been reading a lot about the slow carb diet (tim ferriss). Is this diet considered healthy?

Slow Carb diet. It has many good features like eating foods with a low glycemic index and avoiding sugars and processed foods. It doesn't look worse than the typical american diet which is high in salt, sugar, and saturated fats. The true test of a diet is if you can stick to it longer for 6 months. If you can work it into your lifestyle and sustain the healthy aspects, then go for it.