Reading through the spin.. it's just an object store and pubsub with some demo apps? Like S3 and SNS on Amazon or Google Datastore and Cloud pubsub? That's it?

Reading through the spin.. it's just an object store and pubsub with some demo apps? Like S3 and SNS on Amazon or Google Datastore and Cloud pubsub? That's it? Why would anyone use this instead of AWS or Google?