I've been watching the rise and maturing of AWS lambda and similar offerings with excitement. I've also shipped several microservices in both node and Java that are entirely serverless, making use of API gateway, lambda, dynamo db, sqs, kinesis, and others. For the simple case, I found the experience to be great. Deployment was simple and made use of shell scripts and the excellent AWS CLI. I've been hesitant to build anything serious with it tho. The primary concern has been visibility into the app. The app's operation can be quite opaque when deployed that way. Further exacerbating the issue, we've a few times lost Cloudwatch logs and other reporting due to both configuration issues and improper error handling, but these are things that would have been much easier to identify and diagnose on a real server. Have you shipped anything serious with a serverless architecture? Has scaling and cost been favorable? Did you run into any challenges? Would you do it again?