It runs decently with my system, I ecountered no stuttering and it runs between 40-60 fps @ 1080p with most settings at medium. The cpu never got above 50%, gpu never got below 99% and the highest ram usage was 7.3 GB when I backtracked from the end of the level to before you got the blue key.
I5 750
Gtx 750 Ti
16GB ddr3
The demo was pretty dull in comparison to other Doom starting levels and Bethesda should never of blurted out the term Shareware for a demo with only two levels.