First of all let me start by saying that I think UE4 is an amazing engine and the people at Epic are doing an amazing job with the quick updates and active community management.
However, there are some things that are, in my opinion, in serious need of improvement. It seems that about 99% of the learning resources are focused on blueprints and basic editor usage. Information on c++ programming, and especially custom shader/compute shader development, seem to be kept away from the public eye like some sort of dark ancient secret. It seems a bit strange to me that such vital things are still greatly overlooked.