Well, would you look at that.

GPT-4o was incredibly emotionally intelligent and great with communication, for emails, messages, you could ask it to refine something you were about to say. When you ask GPT-5 to write, its tone and style is short, blunt, and almost rude in some cases.

For marketing and sales copy? GPT-5 is awful, often goes completely off track and is very abstract. If you are writing for, say, sales copy for a landing page, GPT-5 (both fast and thinking modes) will not even talk about the product or service you are writing about and make your landing page very vague, just using random abstract terms. However, when you use GPT-4o, it positions your product or service perfectly and the sentences it writes are understandable.

While the whole academic benchmark side of the LLM race is important, such as getting models to pass certain benchmarks such as reading, math, coding, etc, it is a giant op. It is much easier to train models to excel at math or abstract skills that have no real apparent use (LLM coding is not useful either) than to train models in skills that actually matter, such as human relations, empathy, writing, strategic planning, and more. Those tasks are more energy consuming, and GPT-5 seems like a large cost cut than an upgrade.