I recently decided to downgrade my mobile; (to a Nokia 100, £4.99 on Orange.) there are many reasons for this. I was previously using an Xperia U, Android smartphone. I've had to reset the settings and go back to the stock ROM many times. With each install I've had to remove any/all the pre-installed "crap" apps that I will never use and disable any that won't uninstall, which takes time as there is a fair amount.
I also, for some reason (possibly from gmail contact backups misbehaving?) have multiple contacts of the same name and number, one of my contacts has no less than 7 different entries in my phone book and my SIM is filled with these repeated, useless contacts.
Facebook, which my phone won’t let me uninstall or disable, is becoming both annoying and boring. I usually have small interest in photos that my friends have posted, unless I’m tagged in them. Yet they are sent to me as push notifications anyway, (I don't check FB that often and FB seems to favour posts from profiles that I don't regularly view.) as well as this the whole Facebook “Chat Heads” pop-ups (Favebook Messenger), which in my opinion is the most annoying idea ever! :-p
I am also receiving constant app update notifications, although my phone is set to auto update. Whilst most of the apps need no extra permissions, why do I need to manually press update?
The last and main two reasons on my list are abysmal battery life, I can on some days be charging my phone around two to three times, as well as this the device can become fairly slow and crash. I have also had trouble in the past answering calls, slow opening of the dialler and text messaging app. All because of the small amount of RAM on the device; the whole point of a phone should be calls and texts, no?