I dislike touchscreens in general, but specifically on smartphones it's not just the touchscreen.
The screen is relatively small, so when the phone displays a full keyboard it is difficult for me to hit the key I was aiming for.
Even worse is that since this is a touchscreen, I have zero tactile feedback whether I am pressing the correct key. I can type better on a physical keyboard with the same size keys. If the keys on a physical keypad are smaller than my finger, there is no problem, as I can still feel which one I am pressing. Not so much on a touchscreen.
Making the phone display just the numpad and typing like on an old phone is better (larger keys), but still more annoying than on a phone with physical keypad.
A lot of functions are not obvious. That is, on a PC I can left click, double click (performs some action) or right click (displays menu). On a phone it's tap or hold, but sometimes I have to tap something and then find a button to edit or whatever, some other times I have to press and hold until a menu shows up.
The phone itself is big and uncomfortable to hold in my hand. I am used to holding the phone with one hand and pressing buttons with the thumb of the same hand. This is difficult to do with a big phone and especially with a touchscreen. Making it smaller would make the UI or rather trying to press a key suck even more.
The software is crap. Everything wants an account, logging in and then agreeing with tracking. If I could have pure Linux (something like Debian) running it woudl be better in this regard, though it would make the hardware/UI part suck even more.
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The phone itself is less durable. I am sure there are ruggedized versions, but in general an old phone handles dropping much better. I just need to find the battery and put it back in.
Speaking of batteries, they are hard to replace on most phones. There are ones with replaceable batteries though, so I guess if this was my only problem I could get one of those phones.
The smartphone I actually tried was with Android 2 OS (IIRC), but sometimes I have to handle more modern ones (someone asking me for help etc) and IMO the modern ones suck more than Android 2 as far as UI goes.
Also, I do not really need it. I can call and send text messages from my current phone. I can (and usually do) carry a handheld PC (for example, GPD microPC, but I have a few others) if I need to actually use a computer (which is not often), it is way better than a phone (both the hardware and the fact that I can use normal Linux on it).
Interesting. Here, in Lithuania, 2G (GSM) network is still active and runs great. It's not just old phones, there are alarm systems and various other devices that likely use 2G for calls and text mesages. I have visited Poland and had no problems with my phones as well.
I have a tablet that I almost never use. I got it for free and use it if some stupid site insists on it for identification or if I need to test an android app for a customer. A tablet is a bit better than a smartphone as it is bigger, so I do not have as many problems with typing. Still, it stays turned off for months until I need it.