I don't know about Rings of Power, I have never read the books and it's been forever since I've seen the LoTR movies, but in terms of HOTD, it is my understanding based on the Alt Shift X videos on YouTube that analyze the show and how accurate it is to the books (which I have not read either) that it is not bad at all? Some things are different, but in the most recent episode for example, they mentioned that one change (Viserys Targaryen's final years and death) was welcome by Martin to such a degree he said he'd rewrite the book to match if he could. So the writers of HOTD I think are doing a good job being inspired by the source material and I am so far enjoying it more than I have enjoyed several seasons of GoT.