First 3 seasons were thrilling to watch. The actresses played their characters with such believable wit that it was difficult to look away from the screen. Fiona Shawn's Carolyn was especially titalating.
The will they/won't they dynamic between Sandra Oh's Eve and Jodie Comier's Villanelle did serve the plot as it continued with the hunt for The Twelve — an organisation of powerful people that rule the world and employ Villanelle.
At the end of season 3, there seemed to be promise of an epic conclusion, but once season 4 aired the audience was left to pick up the pieces of a time jump without any explanation.
And it went downhill from there.
Characters were turned on their head, barely recognisable, and hard to swallow after 3 seasons of familiarity. So many questions were left unanswered, and the ending that the writers thought was amazing only left audiences bitter.
We were given an unsatisfying end to The Twelve after 4 seasons of build-up, only for a 10 second montage. The characters' new traits were never explained, and the significant death of a main character felt so unnecessarily cruel.
This is a case study on how the books are way better than the adaption. In fact, the series only worked as long as they followed the books, but writers chose to throw the material into the sea with their main character instead.