I watched the first episode of the 3rd series and hated it. I watched the 2nd one in case I'd been mistaken. I wasn't.
I think you have to watch it from the beginning to really like it. Some of the homour has been replaced by drama as the series have gone on.
I'm finding it really distracting that it's filmed in Barry, every single scene I'm going "I know where that is!". And I keep noticing when they change the geography by cutting things together.
Their house is across the road from someone I went to school with and I used to work in the cafe Robson Green comes out of in episode 1.