Portal is incredibly basic in its puzzles. There's barely any challenge even in the second game. Stephen's Sausage Rolls pushes its basic mechanics to the absolute limits and made me think significantly harder than Portal ever did. Not that Portal is a bad game mind you but it's not very deep as a puzzle game

I love Portal, but it feels more like a tutorial than a puzzle game, because the tolerances on each solution are so large.

It's a fantastic game, one of the all-time greats, and there are tricky parts to execute, but it's not particularly challenging in terms of puzzling.