From the outset, Toy Story 4 seemed like a terrible idea. After the sublime send-off that the third film gave Woody, Buzz, and the rest of the gang, the thought of revisiting the franchise almost a decade after that crowd-pleasing finale felt like a cynical cash-grab – one that risked tarnishing the legacy of a practically perfect trilogy. There were production delays, release date changes, and “creative and philosophical differences” that caused the film’s writers to quit the project – all pretty glaring red flags.
Source: IGN.com Toy Story 4 Review