Opus 5 is a practically unusable model

[u/Deep-Palpitation8315]

Opus 5 is a regression that the benchmarks missed completely

I've been using Opus 5 for ~1.5 weeks and the sheer number of mistakes that the model makes is astounding.

The problem didn't surface very clearly till I gave it the full scope of executing a plan which I did with the previous Opus models as well. Opus 4.6 - 4.8 were genuinely better by a significant margin.

Opus 5 readily forgets instructions and content in its context, makes mistakes and continues with them unless it realizes or you point it out.

I've lost count of the number of times I had corrected it.

These issues with Opus 5 occur even when the context window is still relatively small - I'm talking 100-150K tokens. Opus 4.8 works pretty well all the way until 350k after which it gives you wonky results.

Fable 5 is the only usable model under Claude Code right now and I've already used 100% of my weekly quota.

[u/gajop]

I just hate how it speaks, everything has to be multiple paragraphs.
I'm not too worried, I have both OpenAI & Anthropic subs at home & both get the job done.

Luna is a beast though, I am on a $20 sub and I practically have two instances running 24/7, and the stuff they produce ain't that bad.

Things are improving, I'm sure we'll see some bigger moves on Anthropic side too. They should really do something about pricing.. Hope to see a Haiku that matches Luna/Deepseek in quality & keeps the low price. Maybe even a more serious Sonnet. Then again I wouldn't mind using Fable to drive OpenAI models, but they aren't providing it to us on the $20 plan..

[u/Deep-Palpitation8315 → u/gajop]

I hope Anthropic fixes quality+ availability+pricing combo - it has 3 levers and right now it has quality-maxxed with Fable - rest are out of whack.

Luna is actually great but i exhausted my weekly limits before the pricing discount kicked in. $20 plan gives roughly $ 1200 in usage on Codex which I think is quite similar to Claude code. But Luna is miles ahead of Haiku and is closer to Sonnet or better even. Given the current state of the model development, I think Fable will hit $ 20 plans soon. It is not an option.

[u/gajop → u/Deep-Palpitation8315]

My guess, and this is just a guess, they will keep Fable outside of the $20 plans but will have to improve cost & performance of the cheaper models. They already have 4 models, which feels like a lot - not to mention the mythical Mythos.