The update was swiftly propagated in the Android stores (as it usually is), but for iOS propagation is being exceedingly slow today. As such, Android players are able to get into the game, but iOS is still under maintenance (as the previous update everyone would be on would not be compatible with the new content/fixes the server is sending data for).
Typically iOS propagation takes less than an hour, but it could take 2-4 hours, so we hope that will appear soon so we can force upgrade and release maintenance.