Frankly, it's a bit of a throwback. The stereotypes (parking the second-hand prestige car on the pavement outside the house), settings (dun-coloured wallpaper, polythene sheets on the sofa) and jokes (mother-in-laws) are mostly drawn from the sitcom repertoires of the 1970s. There's even a canned laughter track. You just don't expect to see such dated comedy on twenty-first century television, any more than you'd expect to see, say, Martin Amis in a Toby Carvery.
One could go on. But suffice to say that BBC executives must be concerned by the show's dwindling audience and the number of complaints received by the BBC about the programme suggests that not everybody is finding it very bloody funny.