Okay, I beat it. The time travel concepts in this game hurt my head.
SPOILERS
Overall, I'd give Skyward Sword a 7. A good game, but not what I look for in a Zelda game. My favorite part of the Zelda series is actually not the dungeons, but just the whole getting lost in a world, exploration, and the sense of adventure. The sky in this game really needed more stuff to do, and the surface should have been more than a bunch of obstacles leading to a dungeon. At least put another town down there for one of the non-Hylian races.
The repetition of having to go to the same three environments got old, and so did having to fight The Imprisoned three times (even more if you do Boss Rush). There's also an odd lack of enemy variety: so many Bokoblins. Not to mention the constant text about things you already know. "You got a Blessed Butterfly! Here's what it is! Now let's go to your item screen and show how many of them you've collected!" Or "This is red potion! It fills bla bla bla hearts and you should get it for your adventure bla bla bla."
Anyway, I did like the Kikwis and Mogmas. I think the Sandship was probably the best dungeon.