If anything, I think the puzzles in HL2 are some of the easiest I've played. Why? Because they're all based on real-world physics, and not on hunting for stupid keycards or making a sequence of increasingly difficult jumps. Instead, you're allowed to think your way through them as you would in real life, ie pushing something out of the way, dropping something off of a balcony, etc.
And I still like my dorky HL2 shirt.