It's pretty much a complete package as far as I can see, what programming skills would you need, assuming your not modifying the source(still cannot believe they are licensing the full source, that's 25 years worth of research and blood and sweat there).
We are talking about shaders/effects and some gameplay scripting such as LUA, or I think it's unreal script.....?
C++ for everything programming related and Blueprints (gameplay scripting, actor archetypes seem to be replaced with this as well.) Everything else seems to apply from UE3 to UE4, just learning how the editor works and the various tools available in it will get you far enough to make prototypes without going too deeply.
I've been toying around with it for the past couple of days, and the tools are nice for 20$. You can plop down $19 for one month and then cancel if you would like, they let you keep the source and all you lose by not continuing your subscription are updates and marketplace access (which isn't even available as of yet). Some of my friends have decided to go with 19$ every six months, since that was about how long it took to get UDK updates anyway.