I'm very fond of that film.  Powell had also made documentaries about the Hebrides, and hired a Gaelic consultant to make sure that the language was used correctly.  The song arrangements were a long way from being authentic (most of the singing was done by the Glasgow Orpheus Choir) but the whole thing was done with respect and an attention to detail that was rare at that time.  Whisky Galore wasn't in the same league.