I bought this unit to replace an iPad 2 64 GB with a failed battery. There was no problem updating the iOS from 8.xx to the current 10.3.3. I then reset it and "restored" the iPad 4 with the iCloud backup for the iPad 2. It took a little while to load because I had almost filled up the 64 GB unit and my WiFi internet is not the fastest in the world.
I ordered it with the SIMM slot for cellular but have not yet set that up as my use is almost always on WiFi.