These aren't really spoilers, just tricksy Silicon Knights' references to other Nintendo related things.
Ok, so I assume we've all seen Mario, Yoshi, and the Gamecube in Otacon's lab, but I found another SK reference. I don't know if this is an isolated thing, but on the second floor of the tank hangar there is a door (level 2 or 3, I can't remember which) and inside are two computer screens. One has a blue background with some text. Blah blah blah. The OTHER is an image of SK's website with the little, um...ball design navigation thingies at the top. The larger image on the right is none other than the cover of Eternal Darkness, planets and all.
EDIT: Oh, yes. And I beat the game. It was, in one word, skookum. I don't think that's a word so we'll go with superb. I really liked the cutscenes and I hope there's a way to replay them like the cutscene menu in ED. The action sequences were better than any of the Matrix movies and possibly better than Xiao Xiao. Sadly, I got a total of 2 dog tags on easy mode (7%). And they were practically handed to me.

I don't know what the bandana is for though. It is a MYSTERY!!! (to me.

) This is a must have Cube game.
Oh and is being called a Puma a BAD thing?
EDITED EDIT: Someone mentioned being disappointed that the music from the death of Sniper Wolf was removed, and I just downloaded a piece of music with the same title. The music is exactly the same as the end credits music. Is this correct or was the music mislabeled?