So you upgraded your iPhone to latest  version iOS 6, then lost Google maps and seeing crazy directions in  apple developed Maps app.  If you want Google maps back on your iOS 6 device, here is workaround detailed by Google to adds it’s maps to your iPhone 5.
Workaround 1 [From Google]:
Google Maps is available to everyone using any mobile browser. And this includes iOS6 users. Accessing Google Maps is really easy—just follow the steps below.
1. Open the Safari browser and go to maps.google.com
2. Tap the Share button (on the bottom middle of the screen on iPhone, at the top on iPad)
3. Tap “Add to Home Screen”
4. Tap “Add” in the upper right corner of the screen
5. Now, simply tap on the icon and let Google Maps get you where you want to go!
With Google Maps on your mobile browser, you get many of the same Google Maps features you’re familiar with, including the ability to:
-See your current location
-Get driving, transit, biking and walking directions
-Turn on satellite, transit, traffic, biking and other layers
-Search for nearby landmarks, restaurants and other points of interest
-See clickable icons for popular businesses and transit stations, as well as detailed information such as hours of operation, Zagat scores and more
-When signed into your Google account, access your recent searches, starred locations and My Maps
Google Maps for mobile web browsers provides the latest features without needing to install any updates, no matter what device you use.
Workaround 2 [From Apple]:
Also Apple  detailed instructions (similar to Google) to add  Google maps or Nokia maps to your iOS 6 device:
1.Tap the Share button at the bottom of the Safari screen for the website you’re on.
2.Tap the icon labeled “Add to Home Screen.”
3.Tap the Add button in the upper right corner.
4.Launch the website from your Home screen by tapping its icon
My view :
Although these workarounds will add only Google maps web app to the home screen of the iPhone, which is nothing but a short cut to web-page.I think all iOS 6 device users are expecting a native Google maps for iOS 6 devices. After Apple CEO  Tim Cook openely admitted weakness in  Apple maps and called Google as alternative, now it is upon on Google to deliver an maps app designed for iPhone or iOS 6.