Don't worry, I'm not going to say any spoilers here :-)
WRT spoilers, I'm not too concerned with knowing that some creatures are going to make a return. It's a retelling of the original DooM, after all. What I'm worried about, and what I think other people who say they are concerned about seeing spoilers are speaking of, are rather how it looks. I don't want to see a trailer that will show the new textures, lighting, bump mapping, and other effects, because then I'll expect too much from the game. Better to not have high expectations and be blown away when one first plays it in the pitch black silence of the computer room with surround sound.