There is an interesting and solid look at S1 Tomb of Horrors.
Review: S1 Tomb of Horrors
I have mixed feelings on S1. It's one of the first adventures I owned. I ran it multiple times (my cousin's thief Blackstar went there at least once, and lived). I think I mis-ran parts of it because of the difficulty of the text. It was fun, but it was also a bad influence on us. It set the tone for a lot of play - traps were lethal, often with no save; treasures could sometimes be stingy; games were meant to be hard.
It certainly had to influence the killer dungeons back in the day. DMs often bragged about how lethal their dungeons were. PCs were playing pieces to be expended trying to beat the dungeon. S1 was an example of the type, even if it's more of a puzzle than a monster maze meant to dice up your characters through combat.
But it's an interesting dungeon. It's tough, but it's not impossible. It punishes greed and lack of caution. It's a thinking person's dungeon, and quite possible to get through if you're careful and the GM is fair. It deserves the designation "S" for "Special" but for us elementary school aged gamers it was just one more example of How to Play the Game Right. The modules were gospel, and this was a gospel of strict and lethal play.
It's a module I'd like to run for an experienced group. I like what it's inspired (The Mud Sorcerer's Tomb is an homage that one-ups the original in many ways). But again, it may have been better if we'd never touched it back in the day. We'd have done better with something less special and less lethal.