A 12-hour side-by-side test says Opus 5 feels worse than Opus 4.8 on analysis work

mynaame · reddit · 2026-07-28

After about 12 hours of side-by-side testing, the author says Opus 5 was disappointing on non-coding tasks.

Compared with Opus 4.8, Opus 5 felt lazier, more assumption-driven, more likely to skip reading PDFs and Markdown references, and more likely to answer in blocky chunks with poor paragraphing. For coding tasks, they said the two models felt almost the same and did not differ much on routine development work.

Their conclusion is that Opus 4.8 was more coherent and precise for analysis-style work, while Opus 5 did not deliver a meaningful jump for their use case.

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