OpenAI GPT-4.5 Review — The Most Expensive Model That Lasted Four Months

GPT-4.5 launched February 27, 2025 as OpenAI's largest non-reasoning model ever. It posted the best SimpleQA factual accuracy score of any model at release (62.5%), halved GPT-4o's hallucination rate, and demonstrated genuine improvements in conversational quality. It was also priced at $75/$150 per million tokens — and deprecated by OpenAI just four and a half months later. We review the model that had the shortest commercial lifespan in OpenAI history.