Well, I use CC3 exclusively for the maps I do (for my biggest collection look for the THUNDERSPIRE, PYRAMID OF SHADOWS and KING OF THE TROLLHAUNT WARRENS in the finished map section....or my sig in about 5 minutes). I very seldom do any post work in PS beyond ensuring the scale is done correctly.
Can you do in PS what you can in PS? Yes. Cities, yes, but for myself, I hate the BRUSH look of the buildings, where each building is a separate entity, as it lacks the cramped look cities historically had.
Is CC3 and it's add ons easy to use? I think so. I picked the software up around 12 years ago (When it was CC, then CC2 and CC2 Pro). The interface has never really changed, and if you follow the tutorials, you will be golden in no time.