I switched to a Nokia 8110 a couple months ago, and really want to like it, but the basics are too poorly done. On the 8110 in particular, the keys are quite small, and their debouncing is terrible. I worry the debounce might be the same for other phones in that family, which all seem to have the same guts. A single keypress is very often interpreted as a double-press, which makes T9 frustrating and the predictive mode practically impossible.
There's no way to switch the ringer off, without opening the cover and navigating two layers of menu. The music player is borderline useless, a shame considering it has a microSD slot.
At least on my network (Vodafone NZ), MMS messages don't work in either direction - basically you have to ring someone back when they try to send you one.
The idea of having maps is nice. But, in practice, I've just reverted to noting directions in a notebook that I carry anyway. So, while maps was one of the main reasons I tried a Nokia KaiOS phone, it's not a requirement for the next one.