1. It's far from perfect, but can serve as a substitute for junk food. After six months of switching to Soylent, the cholesterol in my blood had dropped significantly, as verified by blood tests.
2. It's much easier to moderate food intake with Soylent. If you eat out, especially in the US, the portions tend to be huge, and there's often a post-meal slump. Soylent makes it possible to continuously consume little amounts of food.
3. Your body loses the ability to process solid food if you have too much Soylent. It's possible to get addicted to Soylent, and develop an aversion for regular food, and this is unhealthy, to say the least.
4. Cooking and eating home-cooked meals is an essential part of overall well-being. For snacking on-the-go, smoothies are a good substitute. With yoghurt, seeds, and protein powder blended it, it's arguably healthier than Soylent.
Conclusion: Soylent is like one of those fruit juices you might pick up at the supermarket, when you fancy it. Getting cartons of it shipped home every month is harmful to overall well-being.