I have the base M4 Mini.

It is a proper road-runner, especially single-core speed. I pounded the CPU with parallel code compilation to saturation and I couldn't hear the fan. Although it did get warm to the touch.

The major problem with this unit is that it is too small for my cat to sleep on. There are other ways in which I liked the previous Mini format better. E.g. having a few USB-A ports. The power button on the bottom is very easy to press by accident, e.g. when moving the unit back after the cat pushed it down.

5 stars from me overall. I am an experienced Unix user, so although I filled up the 256 GB disk in less than 24 hours I know many ways to have things on external drives. But make no mistake, I ran out before installing any music packages, media or full XCode.