I kinda really started to hate some of the characters in the last couple of seasons. Kate, for example. She is insufferable. It's not like they portrayed her as a flawed person, which I would understand. She is just behaving like a child, she is arrogant, impulsive, and kinda stupid. She always thinks she knows best. AND SHE NEVER LEARNS FROM ANYTHING THAT HAPPENED TO HER. It's the writers' fault, of course. They used a bunch of stereotypes when portraying female characters. So, Kate is the femme fatale, hot chick with a gun, and most of her personality is centered around going back and forth between Jack and Sawyer. It's boring and lazy writing, to be honest. Then, Juliet. She says and does a lot of stupid things during the last couple of seasons. In one moment, she tells Sawyer they all need to go back to the island to stop Jack's plan to blow up the island, and then a few seconds later she is like "We actually have to help Jack". And when Sawyer asks why she changed her mind, she is like "I saw the way you look at her (Kate)". Do women in this show have any other motivation for doing things besides their romantic motivation? I mean, It's such a cringe and pathetic thing for Juliet to say. And this "romantic motivation" is not even convincable. For example, when Jack tells Sawyer he wants to blow up the island because Kate doesn't want to be with him or something like that. I mean, really? Does anyone truly care about people being killed due to the bomb detonation? No, it's all about their superficial love interests.
The show shouldn't have lasted that (6 seasons) long. It's not a bad show, don't get me wrong. But it got really bad in terms of character writing in the last couple of seasons.
The story itself was interesting for me. But I often caught myself rolling my eyes because of how often the show uses the same tricks to play with the audience and cause dramatic effect or revelation. And there are many things they introduced when it comes to the story (too many if you ask me) and I'm not sure if they were able to tie them together in a proper manner. There are also a lot of things happening without logical explanation. For example, why did all of them have to go back to the island? Their motivation for going back seemed illogical and forced. The show also becomes repetitive. I mean, I really didn't want to see for the 100th time Kate escaping from the police and doing her ninja stuff, cutting her handcuffs, etc.
So, yes, it's not a bad show, but it's not a masterpiece either, for sure.