Scratch is the only type of visual programming I've enjoyed using. It's easy to read if you're an experienced programmer because it has the same structure as regular code, and it's easy to read for beginners because everything is broken into large blocks that have what they do written right on them. The way code is structured in most programming languages is actually very logical and intuitive, and it's the most successful system we have so far. The problem for beginners is that they can't figure out if they enjoy programming until they've learned the syntax, which can be very discouraging for some people. I've seen Scratch bridge that gap for people a couple of times, and I think it's probably the best model when it comes to teaching people to code.
I think other types of models would only be useful for situations where writing code isn't the most intuitive way to make something. From my limited experience, a visual system for making shaders is a pretty good idea, because ideally, you don't want to have many conditional branches or loops, but you might have a lot of expressions that would look ugly in regular code.
I think other types of models would only be useful for situations where writing code isn't the most intuitive way to make something. From my limited experience, a visual system for making shaders is a pretty good idea, because ideally, you don't want to have many conditional branches or loops, but you might have a lot of expressions that would look ugly in regular code.