Hi olgeezer,
What I found absolutely critical: As you make your way up through the various floors and rooms of the hotel -- make a brief note of the room number and what is in that particular room. That will save you headaches later when you need to get back to such-and-such a room but you can't remember exactly where it might be.
Otherwise, yes, just jot down what seems important to you. There are various symbols which appear and are important, and will need making note of. Other than that, it's not too extreme.

You can always go back to areas to recheck data if you need to.