Download from play store bug:
It is hard to know if it is a glitch, oversight, someone clicking the wrong filter check box, a deal with a provider to block users of specific phones so they are incentivised to buy a new phone, or an attempt at limiting low end use at launch to avoid battery life complaints etc in reviews, or simply blocking a large chunk of the market to help ease the burden on the servers.... but whatever the underlying case may be, several phones that meet the game's official requirements are listed as not compatible by the android play store filters currently, but only for some regions of the planet and some providers. The app will run fine when installed from a mirror, but hopefully they will fix the faulty filters soon since I'm sure everyone would rather have it installed from the play store. One of my phones, a Samsung Galaxy S3 from Verizon, in the midwest of the USA running os 4.4.2 had this weird problem. I downloaded the mirror copy because I thought I could see why it wasn't compatible in doing so, only to find that it worked better/just as well than it did on some devices I had already installed pokemon go with from the play store. It's a download bug, but I would still count blocking a device that fully meets official requirements and runs the game in top form worthy of noting(especially when ingress can be downloaded). If this was intended do to some hardware issue expected in future releases, I would hope that at the very least the pokemon go requirements will be updated to reflect this fact rather than leaving these seemingly compatible phones a mystery, but given how eccentric the launch has been, my money is on a misclicked checkbox.
Double talk (unbuffered input) errors:
A few specific examples are listed here, but several are missing. They are all double talk errors where the game lags after you tap to signal an action and when you tap it again the signal gets sent twice and causes an error. I've seen it in naming pokemon and transferring pokemon in addition to things listed here such as the pokemon stop spins.