It is made for professional work, but as far as I know, it's mostly used to allow a bridge between that artists and the programmers.
What makes it interesting is that a programmer can code some functionnality to an object in C++ and then create a subclass in a blueprint (that visual bullshit). Then, a 3D artist can plug his model and animations simply with the visual code without any knowledge about programming.
If you use that to code the functionnality, it will be messy most of the time. I was really surprised to see how big of a graph you need to manage just to do a for loop with a condition and a couple variables, just to replicate 4 small lines of code. But sometimes, all you want is to call a function from the engine and it's actually faster to open a blueprint and call it there than to create a C++ class and recompile everything.