These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Iron Woobie: Sue and Karen. The former in Season 2 and a small bit of 3, the latter in 4 when she's stuck trying to impress a group of friends led by a manipulative Rich Bitch.
Jerkass Woobie: How do you make Angela sympathetic again after what she's done? Have her new husband turn out to be violently abusive to both her and to their kids, who now serve as her Morality Pets. Jake and Grandad fit more under "Jerk With A Heart of Gold Woobie". The former struggles with girls and clearly struggles to get out of his parents shadow. The latter has senile dementia and was abandoned by Angela.
When Angela abandons her father to go back to travelling in the US.
Brick abusing Angela and threatening her via his solicitors is also pretty low, even if she is really bitchy. It's revealed he locked his eldest in their room for hours at a time and had his first wife committed too.
Seasonal Rot: Season 4 is considered a low point amongst with characters such as Karen and Ben getting less screen time, and the 'kids talking naturally' gag sounding more like scripted Precocious Child talk.
Tear Jerker: Sue discovering that her dreams to go travelling with her family have been ruined due to Angela running away back to the USA and abandoning her father.
At some point when Granddad's dementia is getting worse, Jake asks Sue if he'll still remember who they are, after being told his memory will just keep getting worse and worse. She replies that of course he will, but you can tell that even she isn't sure.