alt Hacker Newsas someone who uses these models day in out, i can confidently say its more of a marketing gimmick than anything else. don't get me wrong, the model is great, but nits no out of the world than GPT 5.5 or similar ones. I would say just go and try this model for serious work and see the marginal difference. the model wins in some cases and loses in many others. so, what is this all about? hype!
Working on my codebase (~100KLoC across multiple Python modules) I felt that Fable was head and shoulders above 4.x series. It was just relentless and always hell bent on testing and proving its own work. It just tore through problems like an animal. I never seen that behaviour in 4.5-4.8. I can't speak for OpenAI models as I don't use them but Fable was in a different league. Especially when tasked with long horizon goals that involved reasoning at a high and low level to solve the task.