The big headlines on this release are efficiency, with OpenAI reporting that GPT-5.4 uses far fewer tokens (47% fewer on some tasks) than its predecessors).

The ChatGPT Thinking version features a new interaction style, where the model first displays an upfront plan of its reasoning process.

OpenAI released GPT-5.4 in ChatGPT (as GPT-5.4 Thinking), the API, and Codex, calling it its most capable and efficient ...

OpenAI's new GPT-5.4 clobbers humans on pro-level work in tests - by 83% ...