Portal 2 isn't much better than your average quake 2 run. Doesn't involve any sort of problem solving different from any other 3D game. But the story is kinda funny at least, just like some movies.
Portal: Prelude is a free mod with much harder portal puzzles if that's what you want. Portal 2 did substitute some challenge for atmosphere. I've never done Quake 2 but I know Portal 2 had at least a few good puzzles.
