This discussion may contain spoilers!
Okay, so I'm near the end of it, but something in it really gets me. Don't get me wrong, everything else is great. :D I find it really annoying that some of the puzzles aren't straight forward enough. For instance, when you have to check out a book from the library, and there's no evidence a library exists, you can't see it from the harbor, and you usually don't think about taking the bridge that leads to it. There's also the part where you have to find a freaking bucket that is almost unnoticeable. Plus, the hint system can be really misleading at times and doesn't make it clear just what you need to do. About the puzzles, though, let me quote Ron Gilbert himself in his article, "Why Adventure Games Suck And What We Can Do About It"
End objective needs to be clear
It's OK if the objective changes in mid-game, but at the beginning the player should have a clear vision as to what he or she is trying to accomplish. Nothing is more frustrating than wandering around wondering what you should be doing and if what you have been doing is going to get you anywhere. Situations where not knowing what's going on can be fun and an integral part of the game, but this is rare and difficult to pull off.
Sub-goals need to be obvious
Most good adventure games are broken up into many sub-goals. Letting the player know at least the first sub-goal is essential in hooking them. If the main goal is to rescue the prince, and the player is trapped on an island at the beginning of the game, have another character in the story tell them the first step: get off the island. This is just good storytelling. Ben Kenobi pretty much laid out Luke's whole journey in the first twenty minutes of Star Wars. This provided a way for the audience to follow the progress of the main character. For someone not used to the repetitive head-banging of adventure games, this simple clue can mean the difference between finishing the game and giving up after the first hour. It's very easy when designing to become blind to what the player doesn't know about your story.
Puzzles should advance the story
There is nothing more frustrating than solving pointless puzzle after pointless puzzle. Each puzzle solved should bring the player closer to understanding the story and game. It should be somewhat clear how solving this puzzle brings the player closer to the immediate goal. What a waste of time and energy for the designer and player if all the puzzle does is slow the progress of the game.
Puzzles and their solutions need to make sense. They don?t have to be obvious, just make sense. The best reaction after solving a tough puzzle should be, "Of course, why didn't I think of that sooner!?" The worst, and most often heard after being told the solution is, "I never would have gotten that!" If the solution can only be reached by trial and error or plain luck, it's a bad puzzle.