This games sounds sweet. I loved the original, but I beat in a rent. From what I've heard, this game is much longer, which is great.
As for puzzles.. eh. I didn't really like the last Pikmin level, because it was too openly puzzley, and didn't feel organic. It just felt like Zelda or the Lost Vikings, while the rest of the game had a great, realistic survival and nature theme. The last boss, however, was very cool.
Also, I hope they put a limit on the number of Pikmin you can store per Onion - I don't know what the limit was in the last game, but I never reached it. It'd just be way too easy to store up thousands and never run out.
Co-op sounds excellent, as well as single-player with two parties of Pikmin. Very nice. I also think that explains the "more than 100 Pikmin" phenomenon - each character can control a hundred, but you can only control one at a time, and they happened to be together at that time.
Oh, and I wanna be able to control some bulbugs or whatever they are called!