I had preview access for a couple of weeks. I've written up my initial notes so far, focusing on core model characteristics, pricing (extremely competitive) and lessons from the model card (aka as little hype as possible): https://simonwillison.net/2025/Aug/7/gpt-5/
GPT-5: Key characteristics, pricing and model card - https://news.ycombinator.com/item?id=44827794