I don't like the idea of Soylent. I enjoy cooking, eating out, and trying new things. If you are so busy that you absolutely can't manage to make things (even in advance) or eat out, there's likely other lifestyle problems that Soylent won't solve for you.
However, I'm interested in it because of a) whether it is healthy long-term; b) what this could mean for our eating habits/nutrition in the future, and; c) potential ramifications for those who are not well off.
Healthy, fresh food ain't cheap, and if something in the future (perhaps not Soylent itself) can alleviate the nutritional side of things it'd be a step forward. Obviously, fresh food shouldn't be restricted only to the wealthy, but I don't think an option would be bad.
There are still a lot of questions about what constitutes a "complete" diet, how much regulation should surround products like Soylent, and so on.