Why Nintendo OS is great?

Speed!

I remember the day that I got the brand new Nintendo Wii U, the OS was really slow, and I remember to wait more than one hour for the first required update.

Five years later the OS is still slow.

And I just got my 3DS to double check my Nintendo Network ID and man, that think is annoying. Few seconds to open the settings, more seconds to open the NNID, a lot of seconds to connect to the internet...

Now that we saw the leaked Switch Nintendo OS, everything looks fast, clean, like a mobile OS. Finally!

TL;DR: The Wii U and 3DS have a really slow UI. The new Nintendo OS is fast, just compare the time to open and manage the system settings.