I've used both my iPhone 6 Plus and my wifi only iPad
Mini 2. The only negative I've found with the iPad is, like mentioned above, sometimes the screen does get washed out - even with the hood. I've never used an iPad with cellular, so I can't relate those experiences. I've also never used an Android tablet with my Phantom. The one we have (with cellular) isn't compatible with DJI Go and, that being the case, I'm hesitant to try it with Litchi. That tablet is only two years old and won't run Go. My iPad
Mini 2 is pushing three and it has no problems. I wasn't aware of any advantages the cellular iPad had over wifi only, so I'm anxious to hear of any others besides homepoint being changed on the go...
Well, as far as I understand it, there are multiple ways to 'play' with the drone:
1. Manual, where the motion is controlled by all the joysticks
2. Pre-Planned, where you input a set of GPS coordinates, and have the drone go through those (waypoints)
3. Follow Me, where you hop in your vehicle, start driving around, at your drone will follow you.
The drone already has a built-in GPS sensor/receiver so, the discussion below is only for GPS capability of the Tablet.
For #1, no need for GPS on the tablet, unless you want to ensure your home position (for Return to Home) is the latest. You do not want to go fly in a field somewhere, and you drone to think home is 20 miles away.
For #2, again no need for GPS on the tablet, except possibly during programming of the mission.
For #3, the way the drone track YOUR movement, is via the GPS coordinates of the tablet/phone running the App (DJI Go or else). As such, you need a tablet that has built-in a GPS sensor/receiver.
Most/many tablet manufacturers (e.g. Samsung) do include GPS sensors in their product, almost by default. For Apple however, they include GPS ONLY in the high-end Cellular-enabled devices. For WIFI-only devices (iPad and iPod Touch), there is no on-board GPS. As such, if you want to use 'Follow-Me, you need a cellular-capable Apple device. It is not that Cellular is needed (unless you want live maps), it is rather that only the Cellular devices have a built-in GPS sensor/receiver ... Yes, one more reason to be 'upset' at Apple.