aron Hi Del, I'm not so sure. I've been using it and it has shown deep understanding of code I have written. It has actually helped me write better code by analyzing and improving code I have written. But it does have many limitations, but I find it an immensely useful tool for programming.
If what I wrote sounded like "these things are useless", then I wrote it very bad because it's not what I meant. What I meant is "these things don't know and cannot know the semantic and the goals of what you want to do". Going back to the search engine comparison, that either doesn't know the semantic and the goals of what you want to do, yet it can help you (find, in that case) extremely useful resources to improve what you have done.
Without seeing what GPT has done for you, I am convinced that it does not have "deep understanding" of your code, even it it has "shown" you that. What this thing does is that having seen many (and I mean really many) similar things, it can easily find patterns and similarities, and hence give suggestions based on what other things similar to yours were. What at the moment really can't have (because it is not designed to have) is an understanding of semantic and goals (sorry to sound like a broken record, but that's the essential difference). In fact that's one of the reasons why it is so hard to avoid the system producing unwanted material (e.g. instructions on how to do illegal things), if you are following that discussion.