Speaking just for myself here, there are two major areas right now that are really dampening my spirits. One is trying to get up and running with the very base level connective tissue in C++. Things like loading levels, spawning actors, spawning and attaching components. Now I understand that UE is sort of designed for these things to be done in Blueprint not in code, so that may very well be the reason for the lack of documentation, but I feel that is a bit unfair. The choice should be ours, and in my case I wanted to do it in C++ because of this next item… which is Testing. Right now I am really bummed out on using UE4 for my own personal projects because I am finding it very hard to right unit tests for. I don’t like to do the “Unity vs Unreal” arguments, but here is one glaring area. Writing and executing tests in Unity is extremely simple. Dead simple. In Unreal, it is very hard, and a large part of that is due to documentation.
As a whole I feel it is ironically a lot easier to figure out how to connect the dots with code in Unity than in Unreal, which feels completely backwards to me since Unreal is open source and Unity is closed source with just a lighter scripting component, but that is how it feels. I don’t think that is true just how I perceive it and I think that is because of documentation. The C++ side of the docs right now are just really, really lacking IMHO.