The level design isn't exactly spectacular as it's built with a heavily modified version of the Wolf3D engine and the levels are more maze-like than any of those games you mentioned, but all of the levels in RotT are absolutely chock full of secrets - the gameplay is a ton of fun too, mainly thanks to some fairly long and challenging levels, detailed enemies and a very inventive weapon set. It's got a great nonsensical sense of humour as well, which stems from it's unique development as it started life as a sequel to Wolfenstein 3D and had to be abruptly altered when iD cancelled the sequel as they didn't want to draw focus from Doom. Also, the game is notable for introducing a number of firsts to the FPS genre, namely rocket jumping and capture the flag mode in multiplayer, which was up to 11 players and amazing at the time after playing 4 player Doom.