I agree food-replacements should be doable in theory and that the existing products shouldn't be too terrible, but Soylent does not seem to be drawing well on the existing knowledge.
I really want a correctly-executed version of Soylent, but I won't be eating anything from the first batches, because these guys really don't fill me with confidence.
Personally, I'd like a good Soylent too. It'd be useful for my self-experiments, since it'd help tamp down variability from my diet and increase the statistical power. But Rhinehart is doing it all wrong.
Rob Rhinehart's food replacement Soylent now has a crowdfunding campaign.
If you're interested in one or more of these benefits, send in some money! There is also a new blog post.