For me, this game was amazing right from the first level. Of course I had the benefit of starting with my best buddy and playing through the entire game two player, which had a huge impact. I imagine if you played this game single player it wouldn't be nearly as exciting. So my initial impression is certainly going to differ from others in that regard. With that in mind, that my very first touch of 3D World was that of a two player adventure, it immediately shot up past the Galaxy games for me. I don't think I've smiled or laughed so much at the crazy shit that could only happen with two or more people.
Like I said before, it's like a little bit of Smash Bros. in my 3D Mario, which works surprisingly well. Even with the brilliant GTAV and LOU, this is my favorite game this year.