I just had Soylent for lunch. I've been getting ~50-75% of my calories from Soylent for the last month or so (had a DIY knock-off for some months before that). It's super convenient, I prepare 1 bag for 2 days, lunch done. I was travelling last week, and I brought some powder and a blender bottle so I didn't have to worry about breakfast. As others stated, fiber is a bit low, I add some psyllium husk powder, but I wished they'd add more to make it simpler.
As for taste, I think Soylent 1.5 actually tastes pretty good. It's fairly neutral, so it's also great with iced coffee or tea. But usually I prefer it unflavored.
Not sure about Soylent 2.0, shipping all those bottles seems pretty unenvironmental.