The ban on electronics, with the claim that it interferes with the plane's electronics, has always been bullshit.
The old analog phones put a strong, continuous, signal in a narrow band. This was both an interference problem for communications and navigation equipment (due to effects like front-end quieting and intermodulation, even though the plane's gear wasn't operating on the same frequency) and a signal corruption problem for any electronic device with a metallic structure in its wiring that picked up enough signal to drive the electronics out of proper operating conditions.
Digital cellphone signals, whether CDMA or OFDM based (as well as the OFDM based WiFi) are spread-spectrum. The energy is spread out over a broad band and looks like background radio noise to equipment that isn't designed to collect and concentrate it. This is much less of a problem. Any electronics that would be interfered with it (if the phone wasn't within inches of it) would also be interfered with by so much other stuff that it wouldn't be suitable for aircraft at all.
Now that the Analog cellphone network is shut down (and most analog-capable cellphones are retired), and most modern portable computer gear is also designed with spread-spectrum clocks internally (to avoid generating narrowband radio interference due to all those gates switching simultaneously and periodically), these devices are much less of a source of problematic radio interference.
Meanwhile, the avionics has gone through a couple more generations of engineering, with avoiding dangerous failures from passenger electronics interference as a design criterion.
So now is a much safer time to let the passengers play with their toys than even a few years ago.
If that were true the ban would be for the entire duration of the flight, and it would be pretty scarey if flight electronics were so delicate that anyone with a cell phone turned on could screw it up.
"You can do anything you want [when flying] a plane, as long as you don't do it near the ground." This is doubly true for operating a not-designed-for-air-flight radio transmitter in the plane:
- When flying "up there" you have a lot of room to manouver and a lot of time to correct errors or switch modes if something goes wrong with a system. When taking off or landing you have only seconds to react, and have to be accurate with a couple inches vertically, feet right-left, and tens of yards fore-aft to land ON, rather than under, beside, or off-the-end-of the runway (and avoid all the other planes, buildings, trees, antennas, etc.)
- When taking off and landing you're using a LOT of additional electrical, and radio, systems.