Arduino UNO R4: Nice upgrade or troublemaker?

After 12 years, the UNO R3 is finally getting an update in the form of two new UNO boards, the Arduino UNO R4 Minima and the Arduino UNO R4 WiFi (that's how Arduino spells it even if the correct spelling should be hyphenated).

As an educator working with students ranging from teenagers to 60 years old, I had to order the new boards as soon as they were available to see how the new versions will fit in my classrooms.

I've been using the R3 (and its clones) for several years with total beginners, so that's the focus of my review: How will they fit in a beginner environment ? What might happen when a total noob starts looking for tutorials? How many migraines will I get because of weird edge cases that newcomers are sometime better at finding than more advanced users ?

The (ugly) code I wrote for my example are here: https://github.com/iadjedj/lgp_unor4

Resources used in this video :

- UNO R4 Minima :
Arduino Store: https://store.arduino.cc/products/uno...
Datasheet: https://docs.arduino.cc/resources/dat...
Arduino Docs: https://docs.arduino.cc/hardware/uno-...

- UNO R4 WiFi:
Arduino Store: https://store.arduino.cc/products/uno...
Datasheet: https://docs.arduino.cc/resources/dat...
Arduino Docs: https://docs.arduino.cc/hardware/uno-...

- Components datasheets:
Atmega328p Datasheet (PDF): https://ww1.microchip.com/downloads/e...
Renesas RA4M1: https://www.renesas.com/us/en/product...
Renesas ISL854102FRZ-T
(Power Supply) PDF: https://www.mouser.fr/datasheet/2/698...

- Other reviews:
@HomoFaciens review of the board:    • Opinion: The brand new UNO R4, a not ...  
@EEVblog forum: https://www.eevblog.com/forum/microco...