I adore the graphics--they're so beautifully colored. There's such a nice shading to everything, making it look sweet-like.
I love the music. While it's not memorable to me and maybe others, I must say Skyward Sword had one of the best Zelda soundtracks ever. It's just simply divine.
I like the motion play/swordplay however you want to call it, and how Link corresponds to your exact arm/wrist/hand movements.
The storyline was great too, and I don't know what to say about it really.
I liked the dungeons too--they were challenging, and as another user said, "puzzling and the answer was always right under your nose."
I absolutely adore Fi--no doubt about it. I repeat this a lot when I talk about her: she's ironic, she's vague when you need her most and just full of information when you don't need her. I love Fi, and there's nothing you say about her that can change my mind. Yes, she does get a little bit annoying when your hearts are low, when your shield is about to break, when your Wiimote is about to die. But all of these I have no trouble with--as I find hearts, or die so she doesn't have time to tell me my hearts are low, and I hardly ever get enough damage done on my shield for Fi to tell me it's about to break, but it ends up breaking so again she doesn't have enough time. My Wiimote about to die? Psh, I never pay attention to the battery life on my Wiimote so I'm perfectly fine with her telling me it's about to die.