Disadvantages
Pikmin attack has decreased (100% --> 85%)
A day now only lasts for 10 minutes
Enemies are now stronger (100% --> 125%)
Pikmins now need more time to carry things (100% --> 72.5%)
The fruits which can produce 1 bottle of juice has decreased to 0.5 bottles
The fruits which can produce 1.5 bottles of juice has decreased to 1 bottle
The fruits which can produce 2 bottles of juice has decreased to 1.5 bottles
The fruits which can produce 2.5 and 3 bottles of juice has decreased to 2 bottles
Rewards
You get a badge of beating the game in superstar mode