I finished SS today, and I really enjoyed the final boss battle. It wasn't terribly innovative (aside from its implementation of Wii Motion Plus), but it did have a few moments where I found myself thinking, "That's awesome."
After playing through SS in 48 hours I can say that, as a completionist, I would love for them to streamline the game even further. As far as I'm concerned, there is no point in including bug collecting if there is no ultimate goal for doing so. I enjoyed this aspect much more in Twilight Princess where I had to seek out hidden insects in order to receive rewards. Discovering them was a much more meaningful part of the game.
That being said, they simply MUST do away with certain characters who only buy certain things on any given night. There is absolutely NO reason that someone shouldn't be able to buy any treasure you wish to sell on any given night. On top of that, let me enter the amount of how many of each item I wish to sell you, rather than offering to buy them in increments of 1, 5, or "All of them."