✅ Does what it advertises reliably.
✅ Easy to install (Leads are sufficient and good quality wire)).
Limitations...
❎ Does rely on the existence of a neutral where it is installed.
Most domestic wall switches are a single active and switched active to the fan circuit.
This necessitates you either run a neutral down to the switch or mount the unit in the ceiling where access to a neutral is assured.
❎There is no provision to switch fan off once triggered.
❎The time adjuster is very coarse so it is quite fiddly to adjust to the time you need.