Doom

The Good
Doom. Have you ever wondered how did your polygon filled T&L top notch boring new FPS came to be? Doom. One word: Doom.

Doom created the suspense on games, it created 3D enthralling deep architectural beautiful levels, it created multiplayer deathmatch and surround sound. Due to all this, Doom might not have been the first FPS (it was beaten by Castle Wolfenstein 3D by a year) but it's certainly the best. Doom will survive all this crap about "Graphics are most important than gameplay" new bullshit and remain as a cult game in gaming history. Doom.

The Bad
Nothing.

The Bottom Line
Doom is the perfect FPS. It might not be the perfect game (that place I leave to Tomb Raider for various reasons) but it's a perfect FPS.