Pros:

* When it works, it works. We're processing ~100 msg/s in prod right now, for pennies

Cons:

* Only US-Central region support (no cross region)

* Your function runs as Admin (root) in it's project

* Your function must be deployed to the same project as other assets (e.g. can't listen to GCS or PubSub events cross project)

* No way to pass configs/params to a function (it's all gotta be in the code, including secrets)

* Very limited retry semantics (brute force, retry forever)

* No integration with Cloud Endpoints or APIgee, so every HTTP event driven function gets new unique URL

* Building on above, all HTTP endpoints will be public, no auth

* Slow deployments - e.g. took me 45min today to deploy 8 functions