Proper caching done
Easy to include method, can be as specific as needed for versioning (you can include major, major.minor, etc.)
If google goes down, you go down. Well, if caching is done right that doesn’t matter. Plus I’m sure you rely on your host not to go down either…
If google ends the service, like they shut down other services, you have to re-architect again.
So, are YOU going to use it?