Well what do you use it for? I have an Air 2, which is now over 4 years old. But, I use my iPad almost entirely as a consumption device - books, video, browsing, PDFs. A little bit of messaging and mail, or updating a very modest spreadsheet, is as close as I come to "content creation" on an iPad. For those uses, it's still extremely capable and runs iOS 12 really well.
Sure, the new Pro is prettier than my Air 2, and faster, and the bezels are smaller, the screen is nicer, and FaceID seems like a far more natural fit on a tablet than a phone. But $800 (before a keyboard/case/pencil) for a new consumption device, when mine still works quite fine? I don't see the value there.
Now, if you use it for more intensive things than I do, it could be a huge upgrade, which is why I ask, what are you going to do with it?