https://developers.google.com/terms

then go to Google’s issue-tracker and search for the API you are looking to use, check how many bugs are open currently and how long it takes them to resolve

http://issuetracker.google.com/

in case of the APIs i was using a bug could take months till it even gets accepted

often the APIs don’t have versioning, so when they make a breaking change you can’t simply go back to an older version, instead you’ll have to update your code

good thing is that they usually notify when the changes happen so you have some time to make adjustments