Google Cloud Pub/Sub is fully managed and has global scalability with exactly once delivery. Pub/Sub can be used to build event driven systems without the need to manage infrastructure. All you do is create a topic, set subscriptions and trust messages will be delivered reliably with low latency. Review collected by and hosted on G2.com.

Pub/Sub has no multi-level dead letter queues, after configuring a dead letter topic, there's no automatic retry ffrom that dead letter queue. This means that once messages land there, you have to manually republish them. Pub/Sub also has ordering limitations, message ordering is only supported within a single region and requires partioning that is key-based. Pub/Sub has complex IAM and has no built in schema evolution tools. Review collected by and hosted on G2.com.