What is GPT 5.5?

Cursor Composer 2.5 matched or approached Opus 4.7 and GPT 5.5 performance at 10 to 60x lower cost, making it a significant efficiency play for enterprise coding workloads.

“It performed at a very comparable level to Opus 4.7 and GPT 5.5, a little ahead of them on their medium settings and a little below them on extra high and max settings, but it did all that at 10 to 60x lower cost.”

Cursor Composer 2.5 achieved comparable performance to Opus 4.7 and GPT 5.5 at 10 to 60x lower cost.

“It performed at a very comparable level to Opus 4.7 and GPT 5.5, a little ahead of them on their medium settings and a little below them on extra high and max settings, but it did all that at 10 to 60x lower cost.”

Fable 5 was not unique in identifying vulnerabilities in the Amazon report. Claude Opus 4.8, GPT 5.5, and Kimmy K2.7 found the same ones, undercutting claims of Fable 5 superiority on that benchmark.

“Many less capable models including Claude Opus 4.8, GPT 5.5, and Kimmy K2.7 could identify the same vulnerabilities as Fable 5 did in the report.”

Fable 5 resists sycophancy by selectively accepting valid parts of user pushback while holding its position on other points, unlike GPT 5.5 and Opus 4.8 which capitulate wholesale.

“Fable 5 didn't do that. In my interactions with Fable 5, as I was debating with it, it would frequently accept part of my push back or ideas while sticking to its guns on other parts.”

Fable 5 is worth watching as a model that outperforms GPT 5.5 and Opus 4.8 on strategic thinking and writing tasks, with notably better instruction following and fewer common AI failure modes.

“Fable 5, in my limited experience, blew GPT55 and Opus 48 out of the water.”