I'm not going to lie to you; it took me a while to make up my mind about Gavin and Stacey. It seemed to me neither one thing or another: neither drama nor full-on comedy; and its effort to be both must surely be too ambitious. However, the more of it I watched, the more I was being drawn in, and I grew to like the characters, despite myself. Its humour is quite subtle for the most part, though there are several 'laugh-out-loud' moments, and its humour derives mainly from the characters.
The main storyline is the meeting and rash marriage of Gavin and Stacey, from London and Barry (Wales) respectively, and how their families and friends interact with eachother. Ruth Jones and James Corden, the creators of this sitcom, play Nessa and Smithy, friends of the couple, who in turn become embroiled with eachother, adding an extra orbital link between the two families. Domestic dialogue is particularly strong Gavin and Stacey, and within the two families, we learn of their personal and cultural differences. This is very true to life, and allows us to identify with the various situations in which the characters find themselves, but because it focuses on humour, it doesn't become too heavy.
The characters are likeable for the most part, though personally, I find Uncle Brynn extremely annoying (all part of the comedy, I'm sure!) My favourite is Pam, Gavin's mother, who is played by Alison Steadman. She's loud, pretentious, a true drama queen, but warm behind it all. She plays 'hostess with the mostess' on several occasions, aiming at all costs, to make a good impression, which lands her in all sorts of trouble. On one occasion, her obsequiousness led her to feigning vegetarianism, much to her chagrin when she had to keep up this charade in later episodes. She is complemented by husband Mick, quiet and reasonable, who is a very good foil to Pam, as is the case with many comic couples, Hyacinth Bouquet and Richard coming quickly to mind.
So, 'what's occurring' with this comedy? I'll tell you what's occurring: it's 'well lush'! I have revised my initial opinion of it, and two seasons down, I'll be awaiting the third with anticipation!