Personally, I do not think that managed Functions as a Service are a good idea. Functions are too small for my taste. The execution model in which each request is served by a fresh instance is deeply flawed. The pricing is too high for my budget.
All that being said, I can see use cases where managed FaaS is a perfect fit, but only if that would be the only flavor of serverless deployments. But it's not, even though many are putting the equation between FaaS and serverless computing.
We should ask two significant questions when contemplating whether we should use managed Functions as a Service (FaaS) flavor of serverless computing. Should we use them? If we should, shall it be AWS Lambda, Azure Functions, Google Cloud Functions, or something completely different?
So, should we use managed FaaS? We probably should. But that's not the right question. We can almost certainly find at least one good example. A more important question is whether managed FaaS can be the solution for a significant percentage of our workload. That's the question that is much more difficult to tackle. To answer it, we might need first to establish good use cases for deploying and running functions.