I've got a strong distaste for player-puzzles, riddles, and so on. If a group likes doing that sort of thing, great, but I find it's way too easy to run it improperly. Almost every time I've tried it or had it run on me, the puzzle is either pointlessly easy or shuts down the session as the GM waits for the players to stumble on the answer. Granted, it's not fair to judge a tool by its misuse, but this is one tool I've seen work so rarely I don't even try it any more, and I confess it induces an eye-roll from me when it comes up. Again, if it works for your table, more power to you, go for it.
Intelligence is one of those traits (like alignment used to be) which seems to be seized upon by GMs to punish players - either 'you can't do that because your PC isn't smart enough' or 'just because your PC is a super-genius doesn't mean she can solve puzzles better than you can.' I call shenanigans on that kind of thinking, just a kind of 'gotcha' for the subpar GM.
I play characters in RPGs to explore different roles; sometimes the smart guy, sometimes the dumb guy, or whatever. It breaks the flow of the game for me when I sit there and solve an in-game puzzle when I'm playing my INT 8 fighter; it also breaks the flow when I can't solve it, so my INT 20 wizard sits there like a lump. While I'm not quite in the camp of 'RPing is irrelevant to stats & dice,' I do feel that the action in the game should be largely driven by the characteristics of the PCs, rather than the characteristics of the player.
I do confess that my group plays on Friday evenings, after we've all had a long work week (we're mostly in our late 40's); by that time, the brains are a bit fuzzy around the edge, and even tracking all the numbers and stats and conditions can get confusing (and half our group are people like computerists and physicists and the like, hardly alien to math). So my perception is influenced by that.
Again, if it works for you, great - this is just my opinion (even if that makes it identical with The Truth

). I don't like shrimp or coconut, either, but lots of folks love 'em, even put together.
When I run, the challenges I try to present are in-game situations; how to deal tactically with these foes and terrain; how to deal with various factions of NPCs; how to follow and resolve plot threads to best advantage. It makes the game more dynamic and interesting for me. It seems to work for me and my group, where riddles don't.