I love this game and have not completed it, so I appreciate people being discreet about the ending. I don't want to know!
One thing I have to agree with though is the observation (criticism?) that while in most RPGs, you open the game universe in stages, starting from a small portion until you find Item A, then this opens a new world, where you have to find Item B, and so on. In Yume Nikki, the whole game universe starts wide open from the beginning. So exploration will take you a long time, and as there's no mapping, you'd be remember what's where.
Still, tons of fun as far as I'm concerned.