There are too many bugs ruining the gameplay, but devs do nothing about it.
You get kicked out of catching sessions (after wasting items), and kicked out of gym battles (after wasting HP). Youre shown Pokémon that dont exist (because the data hasnt refreshed), and shown PokéStops that should be tappable but arent. Possibly the most poorly coded game Ive ever played.
QuantumAnomaly about Pokémon GO, v1.31.0