I'm actually replaying Riven right now, and at least for me personally, I find it just as new and refreshing as it was so many years ago.
Riven and its siblings (Myst, etc) are the only games that I've ever had to take down written notes to plan how to approach and solve the puzzles. Riven is more than just a play-for-fun-with-no-benefit way to spend my time; it is an intellectual exercise.