Receive various bonuses by playing, catching, hatching and transferring Pokemon will net you twice as much candy as usual. Your buddy Pokemon will find candy in half the usual time.
Adorable pink Pokemon will appear more frequently.
Porygon, Clefable and Chansey are definitely here and hatched eggs will be more likely to reveal a Cleffa, Smoochum, or Igglybuff.
Lure Modules will be far more effective, lasting for six hours that's 12 times as long as the usual 30 minutes.