Absolutely phenomenal.  Trims the fat of the Doom experience to its bare essentials ("I miss the pistol!" said no one ever) while still being a delight to play. Had an added layer of challenge due to the enemies no longer having idle sounds, so I could only hear them if they attack. Evidently the legions of hell finally discovered how to keep their mouths shut. Played it through on browser, happy to pay for a download to go secret-hunting : )