Flux looks like it has the opposite design philosophy of PromQL: it makes simple things harder and hard things simpler.
I probably wouldn't default to it, but I've had to solve some issues that were complicated in PromQL that would probably be easier here. E.g. I had to work on a Prometheus monitoring/alerting setup where metrics were all recorded in UTC, but alerts should only fire during local business hours. We ended up with something like a thousand character PromQL query that was utterly illegible (have pity on whatever poor soul has to update it when DST goes away).
Flux looks like it would have a more legible solution to that, though at the cost of making simple analysis way more complicated than it probably needs to be.
I probably wouldn't default to it, but I've had to solve some issues that were complicated in PromQL that would probably be easier here. E.g. I had to work on a Prometheus monitoring/alerting setup where metrics were all recorded in UTC, but alerts should only fire during local business hours. We ended up with something like a thousand character PromQL query that was utterly illegible (have pity on whatever poor soul has to update it when DST goes away).
Flux looks like it would have a more legible solution to that, though at the cost of making simple analysis way more complicated than it probably needs to be.