Google is rumored to be working on a new map app for iOS, but until then here is a workaround for getting Google Maps back on your iOS 6 device.
- Open your Safari browser, and go to maps.google.com.
- You should immediately be asked to allow the page to use location services, in which case, agree. If you are not, open Settings, then Privacy, then Location Services, and make sure the switch next to Safari is set to 'On'.
- With Safari open on maps.google.com, tap the Export button in the center bottom of Safari.
- This will bring up a menu of options. In the center will be 'Add to Home Screen.' Tap this, and you'll be taken to your home screen, where a Google Maps icon will have appeared. You can then move the icon to where you want as usual.
You won't be able to use Street View, but until Apple's maps are more detailed, you'll be able to take advantage of the richer information about places that Google Maps offers.