Ever finish a game, think about how awesome it is and then ten minutes later change your mind? (Gears of War 3 will be my example)

[miz1q2w3e]

I think I had the same thing happen when I beat ToS:DotNW (so long ago I don't really remember )

The experience was awesome all throughout the game but when it ended, it all fell apart. I was too busy playing the game to notice some of the crap in the story >_
But I still love the game a lot. It's still an amazing game to me (didn't really feel like it suddenly became "just" pretty good like you mentioned)