Nearly perfect documentation
I've Google Cloud's documentation pretty awful, at least when it comes to authentication - which you need to do to get started with almost anything.AWS starts out simple (Paste your access key and secret key here) and you can adopt very complicated practices as your needs evolve; Google Cloud's design and documentation, on the other hand, seems to jump to very complicated from the start (scopes, service accounts, user accounts, projects, application default credentials, PKCS12, access tokens, refresh tokens...)
I haven't found the documentation very helpful at all - or perhaps the system is just too complicated for the documentation to ever be much good.