only me think the development is hard

I’m a game developer come from unity3D, and start learning Unreal for 2 weeks, util i found the Unreal C++ programming is realy sk, even an new create project will easily fall in compile error, I fellow the Battery Video tutorial, well , really sk, code compilation always fail, and It is hard to delete a C++ class, no button found in right click menu, only way to delete is remove it from hard drive and restart unreal. C++ compilation takes time, and the error is vague:
BatteryPickUp.h(19) : error C2535: ??ABatteryPickUp::ABatteryPickUp(void)??: ?Ѿ???Ա??? , Guess later version will impove. by the way, it is hard to create UI, unlike the UGUI in Unity, and the Unreal buildt apk is too large. last , I will keep study the source code.

it is really not that hard. i think is is mostly because you expect things to look like Unity. forget all you know about unity and look at things the Unreal Way.
as for C++ , don’t forget that for most of the things you really don’t need to use it. you can make almost anything with Blueprint , it is a lot easier and more friendly. and you can use C++ to make your own Nodes for Blueprint.
as for UI, i don’t know how it is in Unity but Unreal UMG is Super easy and powerful i don’t know how it looks hard to you maybe it is again because you expect it to look and act like Unity GUi

I did follow that tutorial recently and it worked like a charm, even could spot some of the little errors that where addressed on next videos or in the comments.

I don’t think you are new to C++ based on your comments about working with C++ in UE4
Just a general comment: C++ (compile) errors tend to be more “complicated” then C#

Error codes can easily be looked up with google, The MSDN docs on errors will generally tell you whats wrong.
Although sometimes you need to look at StackOverflow sometimes as the source of the error is a little gotcha or easily missed.