Not the OP but I use AI all day every day and have noticed substantial improvements in the models over the past ~6 months. GPT-5 was a huge leap (contrary to reporting) and so was Sonnet 4.5.
In practice, I upgraded everything to GPT-5 and the performance was so terrible I had to rollback the update.
Depends on what you compare it to. For us who were using o3/o1 Pro Mode before GPT-5, the new model isn't that huge of a leap, compared to whatever was before Pro Mode existed.