Ah, it's kind of meh for me. The twilight sequence in Faron wasn't so bad the first playthrough, because this was the first time you ever had to collect the Tears of Light, so it was a new thing. It was a little spooky, because the twilight was so dreary, but you could put up with that.
Eldin was probably my least favorite out of the three. The kargaroks were annoying.
Exploring wasn't such a bad thing, but there really wasn't much to explore in Eldin. Once you got to Death Mountain, you found your first howling stone, so that made it less boring. But fighting the twilit messangers with kargaroks attacking you and the volcano erupting was quite frustrating.
Lanayru was pretty interesting. I like what they did with the twilit bloat for the last Tear. That was a pretty neat trick. It was also more fun because the gameplay was different, for example, jumping off the bridge (
!!!), flying the giant kargarok, and the landscape was pretty cool as well.
The twilight was a new experience in Zelda, so I can't complain too much. At times, it did feel tedious, but all in all, it wasn't so bad. If I had to rate them (which I will!), I would give Faron a 3 out of 5, Eldin a 2.5 out of 5, and Lanayru a 4.5 out of five. Overall, 3 out of five, but it gets another half for originality. 3.5 out of 5.