"The books are better."
It's a common refrain from fans of any novel (particularly in the fantasy genre) that gets a screen adaptation, from Lord of the Rings to Harry Potter, and it's certainly something we've heard a lot of through seven seasons of Game of Thrones.
As the show has neared its endgame, while George R.R. Martin still shows no signs of actually finishing The Winds of Winter, let alone starting A Dream of Spring, talk has turned to how David Benioff and D.B. Weiss are bad storytellers without Martin's work to guide them. There are kernels of truth in that, especially in Season 7, but even while the show was following the books it still made plenty of changes.
Some, admittedly, ended up disastrously, most notably in their massacre of the Dorne storyline, but also things like their handling of characters like Jaime and Stannis. On other occasions, though, their diversions from the source material actually paid dividends. GRRM has been known to write himself into narrative dead-ends or take unnecessary detours, and Weiss and Benioff - along with their great cast - have found ways of improving some aspects, either through cutting things out, mixing them up, or pure invention.