It's quite a difference. When i made that move, I was amazed at the size difference. Traditionally, I used the Air 2 for the regular iPad stuff like watching movies, surfing the web, email, mainly a consumption device. With the 12.9, the extra screen real estate gives you room for getting some work done. I tried the 9.7 pro and for me, it was just too small to do anything other than the same things that I had traditionally done on an iPad. Split screen is tiny, keyboard is small, and there's just only so much you can do on a 9.7 inch display. Many will argue that with me and say that the 9.7 is big enough for true productivity. Each user is different. It really depends on what you are looking to accomplish with it. For me, the size alone of the 12.9 makes it a much better "laptop replacement' option than the Air 2 or the 9.7 pro could be. BUT, if you are planning on using it primarily as a consumption device, the 12.9 can be a bit bulky or awkward to hold without a stand or keyboard case. Just my opinions. What are your main uses going to be?