They estimate 2-5%
"""
We’re investigating elevated error rates for some Google Cloud Platform users. We believe these errors are affecting between 2-5 percent of Google App Engine (GAE) applications. We are working directly with the customers who are affected to restore full operation in their application as quickly as possible, and apologize for any inconvenience. We will provide another status update by 2015-12-08 12:30 US/Pacific with current details.
"""
We are affected. All our GCS reads/writes.