Lots of disappointments
Season 5 had lots of disappointing moments, including the death of Jon Snow, Arya losing her sight, Sansa marrying Ramsay Bolton and Daenerys facing fierce resistance from the Sons of the Harpy. This made the season more disappointing than pleasant.
It was boring
Some people criticized season 5 for being boring. Apart from the tragic events that happened, many believed that the season was boring and lacking when it came to exciting events.
Suffering of the Starks
A large number of people love the Starks and want to see them win. Season 5 was one of the worst seasons when it came to how the Starks were doing. This made the season depressing for some people.
Based on bad writing
Some people believe that the parts of the books that season 5 was based on were boring and repetitive. Those people believed that George RR martin ran out of ideas while writing, and as a result the season became boring.
Some fans criticized season 5 for its illogical events such as Stannis burning his daughter or Sansa agreeing to marry Ramsay without much resistance. Those people said that the characters weren’t acting based on their true nature in season 5.
Ignoring important parts of the book
Some fans criticized season 5 for ignoring important parts of the book and for twisting the events in a way that they didn’t like.
The death of Jon Snow
Most people didn’t like the idea that Jon Snow dies, especially that many of them had no idea that he was going to be resurrected later on. (See Why game of Thrones should be banned?)
Leaving no hope
Season 5 killed the hope of so many people by either killing their favorite characters or putting them through serious misfortunes. Many people wondered why they should continue watching the show after such events.
Ramsay is undefeatable
Many fans complained about the fact that Ramsay seemed undefeatable. Ramsay was always portrayed as a winner who outsmarts everybody and never loses.
The Sons of the Harpy were annoying
A large number of fans didn’t like how the Sons of the Harpy seemed to be so strong that even the unsullied couldn’t stop them. People got frustrated with the increasing power of the Sons of the Harpy and the constant weakness of Daenerys’ men.
Bran wasn’t there
Many fans didn’t like the fact that an important character such as bran wasn’t there throughout the season. Many fans kept wondering about his fate throughout the season.
Episode 10 was tragic
Many fans didn’t like the fact that the season finale, Mother’s Mercy, was a very tragic episode full of many negative events. (See Why Game of Thrones is boring?)