I think that was the best part of the old sierra games.
They were extremely difficult to play, so you spent a very long time to complete them. And since the internet was something of a myth, you couldn't just look for a walkthrough when you got stuck in the game. You had to figure it out by yourself. (Or you could invite some friends over, and all would be crunched together in front of the screen to try to advance in the game). I remember the way you really admired the one who actually did manage to solve the problem... I mean your jaw litterally hit the floor in pure dazzlement!
Not to mention the incredible euforic kick you got when you after months of cursing, laughter and amazements finally finished the game! It was so good to finally complete something you had worked so hard on! (I think walkthroughs have made games too easy to complete and the exstacy is not there when you complete a game).
This is why I really love those old games, and why I dislike walkthroughs... The magic slowly disappears...