On the Lucasarts moon-logic scale, I would say Sam and Max rates pretty low overall, especially compared to some of the later games they made like Grim Fandango. (I know, I know. It’s a great story with terrible puzzles.) I actually think it’s better than most of the Monkey Island games besides the first one too.
But this genre is very strange about what is and isn’t a difficult puzzle for people. I’d be really interested to poll people in detail and see where they were tripped up, and where things were easy for them.
