I played this awesome, awesome game at the E3. Several times. Every demo level (sans the zomgsecret ones which only big websites guys can acess at closed doors). Here there are some bits of info about 2 aspects that the hardcore seems to care about a lot:
Graphics: It looks as if it is on a console other than Wii. Seriously. I kind of feel tricked by the rest of the developers... nah, screw that, by Nintendo itself as well. Why can't every Nintendo game look like this? This game is the living proof that a proper art direction with time of development can create a visually stunning title on the Wii. And when I say "stunning" I mean "stunning", not "stunning... for the Wii". It looks like a 360 title on SD. Then you can argue about the tricks that they used in order to reach that point (empty leveles, extra pikmin, whatever) but it IS impressive. And beautiful.
Difficulty: People that claims that this game is easy are wrong. It is not that "omg the person that it is playing sucks". It is that this game has challenge, but not in the form that the other games have. This game's difficulty doesn't come from ultra smart AI, cheating enemy stats or mindless repetition of a task or enemy: this game is always giving you something new to learn. Your hardcore experience won't help you here. This game's difficulty relies on the capability of adaption to new situations, as if it were an epic, streamlined wario ware. Do you think that it is easy? The first time that you do anything, it is not easy. It is not easy to walk in round planets even if there's only one enemy on it, because guess what? that has never been done in a videogame. And the same goes for every element. You are chasing rabbits, then you are fighting goombas, then you are transforming into a bee, then you war navigating trough asteroids, then you are walking inside a machine with mobile parts... it never repeats, you are always a noob to this game because once you learn something, the game trows you something new at you.