What a great port. I mean, we never really got a good port that wasn't CD based until now.
Gameplay: the core game is unchanged and still amazing. Also, unlike the snes (yet again) the controls don't feel detached and the response happens immediately. Now that is just awesome and shows that cartridges can handle doom which the snes and 32X made us think impossible.
Sound: the music and sound effects are kind of compressed as I think they are "midi" files which are computer emulated digitized sound/music files which sounds miles worse than instrumental recorded music which we use on CD's and digital data storage's (like downloads).
Final thoughts: With every cartridge port being horrible you'd probably expect this port to suck but it's extremely faithful to the PC version in all respects: graphics (sort of), sound, gameplay, even the framerate (which sucked on just about every console port other than the playstation).
Hints: play this game
2: be ready to get killed… a lot… especially on the difficulties: "ultra violent" and "nightmare".