Adventure games don't suck time like RPG games, as there are usually no grinding involved to "develop" your character in levels or skills or whatnot. Time spent in adventure gaming are usually with dialogue (which are the key factor in making or breaking an adventure game) and with puzzles. And usually a lot of time is spend when you think too much on the puzzle. Beware of the red herrings.
Hmm... I wonder how would an adventure game be like, if everyone you walk across in the town only say 'useful' things like, "Don't go outside the town. There are monsters everywhere." or "Oh my! You look energetic today. Have you eaten your breakfast?"