In theory I want to like Nextflow, but my main criticism is that it's really, really hard to debug programs that pass around lists of Promises (nextflow's dag uses promises as handles on future computations, and functions receive promises and can't easily materialize them and print them.

The caching is often more trouble than it's worth. Also, the little bash scripts that integrate with AWS break if your AWS environment isn't vanilla (our enterprise AWS has a lot of restrictions).