While Whatsapp is nice, Here is the list of things I would suggest added as improvements to the next version/s, all bar the battery percentage were functional on my Nokia 3310 3G (that didn't appear to run KaiOS, or wasn't branded as such):

First and foremost fixing predictive text and capitalisation. Why can't I select it to auto capitalise the first letter in a word, or the first after a full stop? like I can in the 3310 and I could on my Nokia 2100 10 years ago. 
Being able to lock the keypad, my phone often turns itself off in my pocket as the power button is not protected by the keyboard cover. much like my Nokia 2100 could do 10 years ago. 
Being able to use predictive text in Contact searches
Being able to add custom sounds to the notice alerts per app or notice. 
Ability to block numbers in phone without having to call my carrier every time a telemarketer calls (like the 3110 can do)
Battery percentage not hidden in the settings app. 

These and other queries I sent to support and feel they didn't get anywhere. I intend to use the 8110 as my main phone for use all the time, like I have been using my 3310 for the last 12 months. I'm going to trial the 8110 after the latest OS update and see how that goes.