So when, tonight, we encountered some driders, Josh and I both went, "Yaaay, things we can do extra hurt on!"
On the other hand, puzzles are always problematic in gaming, because if you're lucky the answer will be painfully obvious; if you're unlucky, you're going to spend the evening staring at each other and going, "Duh, I dunno, try this. Duh, I dunno, try that." Only rarely do puzzles challenge enough to satisfy, without being exercises in frustration. Unfortunately, by our choice of paths to take, we found ourselves facing two very tough puzzles, one right after the other.
The first was a pretty standard lever trap of the "you have to flip the various levers in the right order to open the door" variety, with the variation being that if you did it wrong you got zapped with a disintegration spell. Fortunately, jamesbarrett knows enough about dungeon design to have nerfed that a bit into just a boatload of damage, understanding full well how un-fun "You guessed wrong, roll up a new character!" is. Unfortunately, even with that nerf, we were loathe to experiment until we were fairly sure we had worked it out, for fear of using up all our healing ability before getting to the Big Bad Thing we knew was on the other side. Thus we spent a lot of time going around and around on various combinations on paper before we actually tried it a second time.
Then, after some relatively straightforward drider-slaughtering (in which every player got to do insane amounts of damage at least once, which is always satisfying), we were confronted with another puzzle in the form of what to do about the big ball of badness that we found. Every time there was violence, the thing grew, and (as there had been a lot of violence so far) it was already dangerously close to blocking us in. Much bigger and it would have started engulfing the party, the dungeon, and then the continent. (Just think of it as a cross between Katamari and a Sphere of Annihilation, and you're on the right track.)
So we figured that if bad juju made it grow, then good juju should make it shrink, and we spent the better part of an hour trying to heal it, turn it, sing it "Put a Little Love in Your Heart," whatever, all to no effect. Finally the NPC fighter/cleric cast a divination spell which told us we were carrying something that would negate it, and I happened to notice on our list of collected treasures a Portable Hole, which did the trick.
We were glad that worked, but also by this time we were all tired and a bit annoyed that none of the other stuff had worked -- which is an inherent problem with puzzles in an RPG. When presented with the premise "evil and violence makes this thing strong," the natural conclusion to us seemed to be that going all Vash the Stampede on it ("LOVE and PEACE! LOVE and PEACE!") should reverse it. "Throw a portable hole at it," on the other hand, came at us completely out of left field, even though it probably seemed perfectly obvious to the person designing the module.
On the ENWorld boards, in a thread about puzzles in D&D, I heard one house rule that I thought was interesting, which was that if the players spent more than 15-20 minutes of real time on a puzzle, the GM told them the answer to keep things moving -- and just didn't give them XP for it. That strikes me as probably being a good compromise ... after 20 minutes on any given piece of a single adventure, be it a puzzle or a combat, it does start to feel like work.
I haven't had it be that much of an issue when I run, partially because I don't use puzzles that much, and partially because when I do use puzzles, they're fairly simple ones. I think the most recent one that gave the characters a little trouble that I recall was when the PCs were up against an evil cleric surrounded by a force field -- and in that case the solution was actually just to pound on the force field until they knocked it down. The players still ended up a bit irritated by it, because they were looking around frantically for the "trick answer" when the actual trick was that there was no trick.
On the other hand, the reason I don't use puzzles is because they're so tricky to do right. I often receive compliments on my GMing skills, and I'm grateful for them, but part of my secret is that I edit out anything that I think is going to trip me up. ;)