They are absolutely great except:
- you need a beefier GPU for transcoding. It heats up fast under heavy load and most builds are fanless.
- you start to have NAS requirements / +2 hard drives, RAID etc. There are a few chinese motherboards/minipc options now that do 6 SATAs or 4 NVMEs (via PCIE 3.0 x1) but you will be quickly constrained.
It is the perfect gateway drug setup though.