Ease and efficiency of use helped by genuine, readily-available instructions...
Ready indication of waiting messages or numbers-called, and a ready way actually to read or listen, and reply to, them.
A note telling you rather more than terse messages on the lines of "57 apps [sic] ready for downloading". I do not download unknown software!
Oh, and the ability to strip out or block easily, without compromising its primary telephonic functions, any software you don't want or need!
I've taken mine, a 4G-rated (whatever that means in practice) "LG some-number-or-other 2017", out of service, unlocked it, removed its card, paid off the 2-year supposedly-PAYG contract. Only need now to sell it, but I don't know how much to ask.