as a kid, i thought it was ok, but not funny enough... and that put me off until a few years back.
the humour is very well timed and judged. one of the main elements is the class divisions - mainwairing is a 'commoner', yet the leader (hence the references to Napoleon dished out by some of the troop). Other members of the squad are of a higher class, yet lower rank. other have seen active service and are resentful of those who are there for medical grounds, etc... it's all about the undercurrents of differences that have to be put aside for the war effort - in real life these people might never mix.
there's also the 'unspoken' elements - 'Uncle arthur' being the main one.
i think the series has got better with age, i can appreciate the subtlety now, the structure and the characters - Godfrey is a very good one, as a pacifist he was ridiculed for not being heroic, until it was revealed that he had rescued wounded troops in no-man's land in WW1. the rest of the troop have enormous respect for his actions and beliefs.
L