Impressive Speech Synthesis: The quality of speech synthesis in GPT-4o is outstanding, reminiscent of Google Duplex, albeit with a more successful execution.

Where’s GPT-5? If Open AI had developed GPT-5, they would have showcased it by now. After 14 months of effort, it seems GPT-5 is still out of reach. OpenAI may be focusing on new features because they are struggling to achieve the exponential improvements expected. The lack of a GPT-5 level model from OpenAI or its competitors suggests we might be experiencing diminishing returns in AI development.

Incremental Upgrades: The key takeaway from the blog post is highlighted in the figure below. It reveals that GPT-4o is not significantly different from GPT-4 Turbo, which itself is only a slight improvement over GPT-4.