Some good scares, nice story, suprising twists, and a whole lotta hell.
The game play is pretty fun, though it get's somewhat repetitive. You basically run around, some enemies pop up, you flinch, you shoot, you kill, you run some more. At first the way enemies pop up out of nowhere and shriek at you will make you jump, but after a while you get so used to it you hardly notice. You have some decent weapons, although some do feel like clones of others. Besides all this, you constantly have to switch to your flashlight to be able to see in the dark area. Make no mistake, it is tideous at times, but otherwise very fun.
The story is interesting, but it isn't worked out enough threw the game. It feels a little incomplete. There are many twists as well though, you'll be guessing and predicting all the time. If they had only pumped some more feel into the story. Shame.
The graphics are good, but you'll never find yourself thinking anything looks 'too real'. Nothing much to say here. Everything is well made, smooth looking, and fits nicely with other objects or characters.
Conclusion: Doom is a hellafun (Terrible pun, intended) game that everyone should try. It's hellish feel is definitely worth experiencing, and you'll spend long, dark hours alone in your basement playing this.