Everything the first game had plus more
Pikmin 2 is a great example of how games can improve on their sequel, add multiplayer mode, which does seem to work with this title and the introduction of caves is another good idea. Caves are dark, dingy and full of hideous monsters that want to kill you. Where as the surface is light, colorful and full of hideous monsters that want to kill you.
What the game lacks is an in depth story. Most of the game you find yourself finding treasure, taking it back to the ship, find some more, do the same. Over and over again so it came drive you to the point of insanity.
The Bottom Line
Cannon fodder with flower headed gnomes.