I made a brief stab at it a while back but found the whole 'Unreal' experience to be unreal. I had to keep downloading stuff and their file arrangement was incomprehensible to me. Instructions I followed didn't work either.
I figured out how to download a few models. there's been some things in unreal that I haven't seen anywhere else (amusement park stuff, retail stores) that I'd like to get my greedy little hands on.