GPT-4.5 Feels Like a Letdown But It’s OpenAI’s Biggest Bet Yet

It’s not a setback but the setup

I. GPT-4.5 is the step back before a big jump

OpenAI has launched GPT-4.5 (blog post, system card, demo), their latest and largest AI model. They’ve been hinting at it under the name Orion for more than a year, at times confused with GPT-5. It’s finally here and it is… underwhelming. Or at least it looks underwhelming. This post is about why this nuance between “is” and “looks” is fundamental to understanding what’s going on.

You probably have a lot of questions: Why did GPT-4.5 get worse benchmark scores than models launched months ago? Why did OpenAI wait more than a year to release a model that’s not state-of-the-art? Why is it much more expensive than previous OpenAI models and rival offerings? Why have they made it so large if the pre-training scaling laws have plateaued? If they’re so obsessed with reasoning — getting good performance on math and code — why are they suddenly focusing on creativity, intuition, and emotional intelligence?

Thankfully for you, I have the answers. Thankfully for me, OpenAI’s lack of transparency — and its missed opportunity to market this interesting model effectively — gives this newsletter a purpose.

Anyway, we will go over GPT-4.5’s specifications and benchmark evaluations. I will report what OpenAI has shared in the demo and the system card (also what they’ve quietly changed after…