Vibe Check: GPT-5.5 Has It All

by Katie Parrott in Vibe Check Midjourney/Every illustration. Was this newsletter forwarded to you? Sign up to get it in your inbox. Frontier models usually take a while to get used to. You have to learn their slow spots, when they need extra prompting, and when to keep a close eye on the output. GPT-5.5, out today, feels easier to settle into. It’s fast enough to use constantly, personable enough to collaborate with, and assertive enough to carry a plan through serious engineering work. It’s better at writing than any OpenAI model we’ve used in about a year, and it produced the strongest result we’ve seen on our new Senior Engineer Benchmark, which measures how well models can rewrite a messy production codebase the way a senior engineer would. It’s rare for a model to feel easier and stronger at the same time. The big insights from our testing: Best on senior-engineer coding. GPT-5.5 scored 62.5 on our Senior Engineer Benchmark versus 33.5 for Opus 4.7. Humans still score in the high 80s and low 90s. The twist: GPT-5.5’s best run used an Opus-written plan. A real writing comeback. It’s the strongest OpenAI model we’ve tested in a year, with cleaner structure and smoother logical progression than Opus 4.7. Strong everyday knowledge work. GPT-5.5 beat Opus 4.7 on dashboards and felt dependable for creating client deliverables or customer support replies. Best with structure. GPT-5.5 shines with a plan, an existing system, or a tight feedback loop. Opus 4.7 still has advantages on one-shot vibe coding, PowerPoint, Ruby, and some broad product-design tasks. The full Vibe Check has the benchmark results, Reach Test ratings, pricing, screenshots, and advice on when to reach for GPT-5.5 versus Opus 4.7. Read the full Vibe Check And watch our video Vibe Check with Dan Shipper: Katie Parrott is a staff writer at Every. You can read more of her work in her newsletter. We build AI tools for readers like you. Write brilliantly with Spiral. Organize files automatically with Sparkle. Deliver yourself from email with Cora. Dictate effortlessly with Monologue. Collaborate with agents on documents with Proof. For sponsorship opportunities, reach out to [email protected]. Subscribe Click here to read the full post Want the full text of all articles in RSS? Become a subscriber, or learn more.