1. I have to agree. Before I played Skyward Sword I had been playing Twilight Princess, so as soon as I switched over to Skyward Sword, I basically just ran through everything. There was no huge challenge for me and it was horrible. It made me a little sad that such a hyped game had no challenge to it at all.
2. I didn't notice how short the dungeons were, but they were fun(Ancient Cistern+rope and bad guys= OMG RUN LINK!). I especially like the Indiana Jones moment in the Fire temple, or whatever it was called, when you run away from the boulder.
3. I felt the same, there was no need for exploring in Skyward Sword, it was disappointing. Though I wish I had known about the Hylian Shield before I passed over to Hero Mode(I think I need a punch in the face for that one). There was no challenge getting to new places and the world was a lot smaller compared to Twilight Princess and Wind Waker.
4. I kinda agree with Ign, the game may have fallen short in many places, but it made up for it with a wonderful adventure(Though the whole "Prove Your Worth" thing got old fast). There was plenty to do after you made it to Demise and there are plenty of side quests to keep you occupied in the mean time when you get bored, but eventually you have to move on and complete quests and story sections to move everything forward.