I think the real issue with Skyward Sword is not so much liner aspects of the game, but rather Fi's nagging. What could have been a relatively free experience was made linear by Fi constantly giving you direction, even when you didn't want it. For me at least, it goes without saying that Skyward Sword was fantastic, but I do hope that Nintendo took notice of comments concerning aspects that made the game feel more linear then it was (if the text in Hyrule Historia is any indication, they've taken note and will fix it for next time).
That said, I'm a little torn on multiplayer. I'm trying to figure out how that would work, especially since each WiiU only comes with one WiiU Gamepad (and I remember reading somewhere the WiiU can support up to two at once). Absurd peripheral purchases, not exactly the best way to get your game out there.