We have a number of different use cases at FundApps, some obvious like automated tasks, automatic DNS, cleanup AMI's etc, to the more focused importing and parsing of data from data sources. This is generally a several times a day operation, so lambda was the right choice for us. We also use API gateway with lambdas, its a small API, about 2 requests per second on average, but very peaky during business hours, its response and uptime has been excellent.

Development can be tricky, there are a lot of of all in one solutions like the serverless framework, we use Apex CLI tool for deploying and Terraform for infra. These tools offer a nice workflow for most developers.

Logging is annoying, its all cloudwatch, but we use a lambda to send all our cloudwatch logs to sumologic. We use cloudwatch for metrics, however we have a grafana dashboard for actually looking at those metrics. For exceptions we use Sentry.

Resources have bitten us the most, not enough memory suddenly because the payload from a download. I wish lambda allowed for scaling on a second attempt so that you could bump its resources, this is something to consider carefully.

Encryption of environment variables is still not a solved issue, if everyone has access to the AWS console, everyone can view your env vars, so if you want to store a DB password somewhere, it will have to be KMS, which is not a bad thing, this is usually pretty quick, but does add overhead to the execution time.