The idea behind it is that some people don't have time to cook, or the inclination. For myself, it's a combination of not having the willpower to bother, and the fact that eating for one is difficult without having oodles of leftovers. Most grocery stores are designed around families, and it costs me a disproportionate amount of money for food that often goes to waste. Basically, I'd rather try this stuff than eat out all the time, because it's likely more healthy than fast food.
I made a video of me unboxing, making, and then trying the Soylent. The entire video is embedded below, or if you want links to each specific section, find them underneath the video.
Unboxing the Soylent
Preparing the Soylent
Consuming the Soylent
So overall it was a bit gritty and bland, not fantastic, but not terrible, either. Would be much, much better with something for flavour, like strawberries or banana. I'll have to invest in a food processor and give that a whirl. But it definitely has promise. I'll be eating the rest of that jug, as well as making more later. But as far as healthy calories for my dollar, it's hard to beat about $4 per meal for a single person living in an expensive city, and it'll definitely make for good emergency rations, too.