'Titanic' was pretty much the biggest film of the 1990s. It smashed-box office records, it launched the careers of Kate Winslet and Leonardo di Caprio into the stratosphere, and gave the world 'My Heart Will Go On' by Celine Dion. Even though all of us knew how the movie was going to end, it didn't stop us enjoying the story, and crying at the end. Given its success, it's a bit of a surprise to find out that Kate Winslet doesn't like it.
For once, though, this has nothing to do with the script, or the character, or how the film was received. Winslet is just hyper-critical of her own performance. She doesn't feel like she played the part well, and believes she did a particularly bad job with her American accent. For that reason, she can't watch it. That's a shame. You were great, Kate!