I have not recieved my 12,9" yet, but i've had a first and second gen iPad Air before.
When I had those, the iPad felt just like a bigger iPhone (which was pointless for me). This is why I now, a few years later, opted to try the 12,9" because of the current iPadOS14X (and new iPadOS 15) which has had quite a few updates and has changed how we use the iPad. The bigger screen is a must for me since otherwise it simply feels like a slightly bigger iPhone.