Quests are just as much about implementation as concept. I don't quite remember where I read it, but I saw a preview of Oblivion in the past few days describing a quest in which you enter an oil painting to search for a missing painter. The entire world inside the painting is done in oils. I thought that was fairly interesting, and while the kernel may be "retrieve the lost guy," the environment adds something to it.
Don't judge the game until you actually play it.
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Ha! I've played a NwN community mod like that ... (without the change in rendering style to indicate the PC's surroundings were in a virtual world in the virtual world of the mod). I think it was In The Footsteps Of Dante, or the sequel.