Like others have mentioned, the Google Places Autocomplete API is missing some important functions. Case in point, Google will not validate that the street number is real, and they also will not put it into a standardized format. So, it is the user's responsibility to enter that portion of the address correctly.
Google also won't predict PO Boxes or apartment numbers. So, if you are using their API for shipping, address cleansing or data governance, you may want one that will validate the building number, autocomplete the unit number and standardize the information.
Full Disclosure, I work for SmartyStreets