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GPT5 is worse than 4.1-mini for text and worse than Sonnet 4 for coding

10 points by hitradostava ↗ HN
It seems that OpenAI have got the PR machine working amazingly. The Cursor CEO said it's the best, as did Simon Willison (https://simonwillison.net/2025/Aug/7/gpt-5/).

But I've found it terrible. For coding (in Cursor), it's slow, fails with tool calls often (no MCP just stock Cursor tools) and stored some new application state in globalThis - something that no model has ever attempted to do in over a year of very heavy Cursor / Claude Code use).

For a summarization/insights API that I work on, it was way worse than gpt-4.1-mini. I tried both mini and full gpt5, with different reasoning settings. It didn't follow instructions, and output was worse across all my evals, even after heavy prompt adjustment. I did a lot of sampling and the results were objectively bad.

Am I the only one? Has anyone seen actual real-world benefits of GPT-5 vs other models?

7 comments

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tim_angus
And yet the media keeps using the term "exponential improvement"...
8thcross
I tried it with cursor-agent, their cli - and it generated better code than expected. YMMV. It was more thoughtful and strategic than the other frontier models.
canerdogan
GPT-5 isn’t really a brand-new model in the way people think. From what I’ve seen, the goal was more about reducing costs and unifying the interface than releasing a totally different architecture. Under the hood it is still routing to models we already know, just picking what it thinks will give the “best” result for the request.

That can be fine for a lot of general use cases, but if you’re working in specific domains like coding agents or high-precision summarization, that routing can actually make results worse compared to sticking with a model you know performs well for your workload.

softwaredoug
I feel like they should have let GPT 5 overlap in experimental mode for a month or so. It took a while to get the kinks out of GPT-4 until people trusted it. Just switching it on is really hurting their brand.

The fact they didn’t do this makes me think their finances are in very bad shape.

cellis
I have not found it to be better than Sonnet. I wrote this on another thread:

Claude Code certainly not as easy to engineer with, though it is less expensive. For instance the @feature isn’t as robust as cursors ime. Also no shift+enter is quite a pain. Linting doesn’t “just work”, cursor with Claude 4.0 max is really thorough, I think even better than GPT-5. Not that Sonnet is better but that whatever “ensemble” of models cursor uses with sonnet seems to both adhere and tool call better than with GPT-5. GPT-5 often says what it will do and then says “say go and I’ll go” or says “you should run command x”, but doesn’t just DO it. Also for bug fixes in difficult codebases nothing beats Gemini 2.5 pro

blurbleblurble
Really struggling with GPT-5 in all the clients I've used (currently using claude code router). This is the default openrouter endpoint. It's opaque, slow, ridiculously terse, botches basic tool calls and edits, pauses constantly even when I ask it not to. It does seem "sharp" at analytical tasks but it's just clunky to work with.

I'll try with cursor CLI but am hesitant to ditch claude code.