I recently used c.a.flow for a program that reads files from s3, massages the data a bit, and writes to a database. The code came out very easy to understand. The challenges were:

- getting back pressure right. You need to tune the buffers for the input chans correctly, which takes some thinking, and in my case, some blowing up in prd.

- flow monitor (the UI for debugging flows) can't handle large process states, which makes it pretty much useless for my program.

- understanding the flow as a whole (rather than specific processes, which are easy to understand in isolation). For example, answering questions like "why hasn't this process received a message for a while?" was tricky.