I didn't start off disliking it, I'd say I was neutral. But over the years as I've seen it again in part or in whole it's gotten worse. I don't like the story, I feel it's too simplistic. Gump goes through a series of events without ever evolving as a character. To me that conveys a theme of "If you blissfully except ignorance your life will be fine." Also, the dialogue is inane and filled with deliberate catchphrases
I also don't like Hanks performance. It's a novelty, more of a caricature of mentally disabled people than a genuine performance. I also don't like the directing. It was flat and uninspired, certainly not worthy of an Oscar.