Puzzles in context

Last week my wife and I invested in a Nintendo DS. The free game we opted for was Professor Layton and the Curious Village, a classic point and click adventure in which you are tasked with solving the mystery of the Golden Apple, a great treasure hidden somewhere in the small, curious village of St. Mystere. Along the way there are other mysteries to solve as well - inheritances, disappearences, murders and the like.
There are examples of gameplay in the link below, the content of which is pretty much lifted directly from the game.
http://professorlaytonds.com/curiousvillage/

The twist to the game, that sets it apart from other point and click mysteries, is the blatant use of puzzles. Apparently everybody in St. Mystere is obessed with puzzles, and will often only release the information you need if you solve this one riddle they have. Hidden riddles abound throughout the town, secreted in alcoves, bushes and bottles, and the two main characters, Professor Layton and his apprentice, Luke, are also obsessed, posing riddles and brainteasers for each other at every turn.

You cannot progress through the game without solving a set amount of puzzles, and certain key puzzles. There are also hidden games and bonuses you can unlock.

It is very addictive. I've racked up about 9 hours play and solved 90 odd puzzles. My wife, who is not a gamer by any account, has played over 13 hours and solved 103 of the 130+ puzzles.
We've only had it a week.
It is surprisingly addictive.

It has also gotten me thinking about puzzles within RPGs.
My experience of puzzles in Roleplay, tabletop or live action, is not a good one.
The existence of a puzzle usually jars - why would the grand wizard use a block slide puzzle as a lock for his spell book? Why should the shadow spirit demand to know the answer to this riddle about legs and times of the day (which is clearly 'man') before letting the party entry to the tomb? Why do you need to 'speak friend and enter' to get into the mines of morias?
The puzzles used are usually either too simple or too hard - Great, I cannot progress through this door because this fiendish logic puzzle requires a level of maths knowledge I simply do not have! We fought through 17 rooms of Orcs, got to the final encounter, and it was a real anti-climax. Just a wooden puzzle sat on a table with a note saying 'solve me and pass'.

What I like about Professor Layton is that it 1/ provides a clear context for the use of puzzles that works naturally with the narrative and gameplay, 2/ gives an indication of the difficulty level of each puzzle, 3/ has a finite resource based  'hints and tips' buying system, so you're less likely to be stumped on a puzzle, 4/ rewards you for solving as many puzzles as you can.

I'm now thinking about ways I can use puzzles in future games that fit with the setting and situation, and provide a comparable challenge for the party.
And that aren't crap.