spacedog:I haven't heard of reports of it breaking other apps as most of the apps still use google's data so they continue to work.
Once you upgrade to IOS6 google maps is effectivly gone. It gets replaced by apple maps when used within apps. Trademe (property section you can view map of a house), and RealEstate app for example continue to work, but you just see Apple maps instead of Google within their Apps. I find the Google Earth app is good now if you need decent satellite pics.