Here are some spoilers in case you might not have played Doom... which I find improbable:
I seem to be recalling a certain landmark game in the first episode of which you fought 2 giant monsters (easy, even if all you have is the pistol) and a flock of demons, and after you beat those you have to teleport into a really dark room where you are confined with a bunch of zombies and you die.
This is Knee Deep in the Dead, Doom's first episode. And for a while that was Doom's only episode. You could not resurrect, continue the game or explore areas you might have missed, your only option was to restart from the beginning.
Shut up already, enjoy the game you got and be prepared for Rage's next episode.
I've played em' all. Doom2 was the bomb for Doom actually. Used to run through the first 6 levels on nightmare, my son could do about eight.
Used to smoke through Doom.
I have nearly 1000 Doom and Doom2 wads, most of the competition H2H wads and I have many thousands of hours in the game.
Rage is a flawed masterpiece. An empty game on several levels but a mechanical tour de force. As a shooter game it's overshadowed by quite a few superior games with much more content and immersive characteristics. Both of the Fallout 3D games are better games. The Stalker series is head and shoulders above Rage on almost every level but eye candy.
id makes great games but time has passed and the bar for the "game" part has been raised a lot. Rage is a bright happy console game which is fine but it does not compare to many PC games for real content and immersive experience.
It was about what I expected from the clues we could glean from the demo/ads. I am enjoying the game and don't feel too ripped of, maybe $10 or so.

The cars are fun but I did not buy the game to race cars. The environment is pretty but I hate invisible walls and despise corridor shooters so Rage is not wonderful on those levels for me. I like having to use my head and figure out some way to deal with a situation that I cannot just shoot my way through. There are none in Rage. Pity.
Nice engine id. Now make a killer GAME with it.