I’ve used it for a couple of hours to help with coding and it feels very similar to gpt4: still makes erroneous and inconsistent suggestions. Not calling it 4.5 was the right call. It is much faster though.
The expectations for gpt5 are sky high. I think we will see a similar jump as 3.5 -> 4.
That doesn't imply that it's GPT-5. A GPT-4 training run probably doesn't take them that long now they've acquired so many GPUs for training GPT-5.
Pretty sure they said they would not release GPT-5 on Monday. So it's something else still. And I don't see any sort of jump big enough to label it as 5.
I assume GPT-5 has to be a heavier, more expensive and slower model initially.
GPT-4o is like an optimisation of GPT-4.
The evidence for that is the change in the tokenizer. The only way to implement that is to re-train the entire base model from scratch. This implies that GPT 4o is not a fine-tuning of GPT 4. It's a new model, with a new tokenizer, new input and output token types, etc...
They could have called it GPT-5 and everyone would have believed them.