Fail art will still look better with full blown postfx in unreal 4 than it does in unity free. The first look people have at screenshots of your game, is mostly what makes them decide "try out" or "nahw"
ya obv
i didn't think unreal was part of any of this, and i certainly wasn't meaning to imply that unity free is a highly-complete, superior engine. i'm just saying that good game developers can make do and create some really cool stuff despite the limitations that are there. obviously, this won't be sufficient if you're constantly jumping through hurdles (edit: meant "hoops", but i think hurdles is actually a better metaphor) to get the engine to work with your ultimate goal, but unity isn't just a bad game machine.
in the end (to kinda reference the video kingdaro posted here awhile back), every engine sucks in their own unique way.