When it switched from being about Lee Mack trying to get off with Sally Breton, especially when Tim Vine was in it, it was hilarious. Then it was a fast and clever comedy with adult humour.
Series 8 metastasised not just into a family sit-com but the blandest, mundane, most inoffensive sort of thing possible. Mildly amusing but not funny.
The two shows are so different that they really should have changed the name of it. So much so that when you say you like Not Going Out to someone, you have to qualify that by saying: the early seasons only of course. The two shows are as different as 1970s Genesis with Peter Gabriel to 1980s Genesis with Phil Colins.