If I can play on my iPhone 4S, even as they say it won't work, I am sure your phone is fine, Siipu. :) It only crashes when the peeps got off work for me as well. xD
A tip is to get a power bank, and keep it with you while out, incase you need to charge. Also, don't leave without fully charge your device from home. xD The 3G net and the app itself eats battery like cake, and then it might be a time when the sun is shining, and yo need to increase the brightness of your screen, which also drains battery.
I was wondering if you could use the game in Low Power Mode, without the screen locking?