The first dissapointment in the DOOM series
Final DOOM came out nearly two years after DOOM II and uses the same engine, monsters etc. as that classic game. However, while DOOM II got it all right, Final DOOM gets it all wrong.
Final DOOM is much more uneven than either of the first 2 DOOM games. Instead of gradually increasing the tension in the game, Final DOOM throws out most of the more menacing monsters at you right at the start of the game, on the first levels in fact! From there on, the game does this each level until you get bored to tears doing the same thing over and over. Because of this, the game never really gets very tense or gives any kind of adrenaline rush. Instead, unlike the first 2 games it feels like a chore after a few levels, since you will just be fighting the same monsters through the remainder of the game.
I didn't like the level design for Final DOOM as much as the previous DOOM games either (especially DOOM II), none of it feels especially creepy or keeps you fearful of what lies behind the doors. Since you have already fought plenty of Hell Knights, Mancubi, Cacodemons, Demons, Revenants, Arachnotrons, and Pain Elementals by level 3 (lol), only something like a rare Cyberdemon, Spider Mastermind, or Arch-vile could scare you for the rest of the game.
For a game that was released shortly before Quake, Final DOOM offers very little graphical or sound improvement over the first 2 DOOM games. Its nice to see a game with 64 levels, but 64 levels of dissapointing gameplay is still a dissapointment.
Final DOOM is not a horrible game, but for those who want to play it, your best bet is to get the DOOM Collectors Edition, which includes the far superior Ultimate DOOM and DOOM II as well.