Google Maps on iOS has always been a step behind the Android version. Slowly, Google has been porting features, but it has been a slow process. The latest update continues the process, bringing forth restaurant waiting times.
Version 4.47 rolling out now will display wait times for over a million sit-down restaurants. The new interface displays hour by hour wait times, and will show average wait time for each hour.
The update is adding a few other features as well: the interface has slightly been tweaked to ease the process of finding reviews and public transit data has been improved.
The Google Maps update is rolling out to all iOS devices now.