Not the author, but I'm in a discord with him, I believe the main selling point here is that it allows you to manage your updates and conversations in a branching pattern that's saved. So if you can't get the AI to do something you can always revert to a prior state and try a different method.

Also it doesn't work on a "small view of the world" like Copilot from when I was using it could only insert code around your cursor (I understand that copilot pulls in a lot of context from all the files you have open, but the area it can modify is really small). This can add/remove/update code in multiple files at once. But it'll also just show you a diff first before it applies and you can select some or all of the changes made.