I thought they were very clever in that the solution is always available to you when you reach them but isn't obvious, the first one I encountered I thought to myself "Oh man, people are gonna be floored by this" because in this age alot of gamers have no ability to act without direction - why do you think war games are so popular, it makes you walk around doing something a guy is shouting at you to do, I have completed every puzzle I have encountered and I think the one that took me the longest clocked in at a good 5 minutes of exploration until I realized their was a room opposite of it behind a hidden wall that mirrored the correct sequence, very clever every time I encounter those things.