1. No battling or attacking wild Pokemons unlike in the hand-held device version. One of the satisfying and challenging aspect in playing the original Pokemon game is to weaken first the Pokemon before you can catch it.
2. All those who dislike physical exertion, such game can become a chore.
3. The game is so engaging that as a result the player become distracted causing them to stepped on poops, fell into puddles of mud or stumbled in broken drain systems.
4. The players might possibly be vulnerable to criminal elements and susceptible to phone snatching, rape, robbery etc.
5. If you want to get ahead of the game, you will have to purchase items involving real money.
6. Taxi fare or additional gas budget if you're really determined to catch all the Pokemons in your area. (Strictly don't play Pokemon Go while driving)
7. No trading of Pokemons yet.
8. Battling other player is restricted or exclusive only in PokeGyms. Players may cause disturbance to the employees working in the building or establishments which happens to be a PokeStop and much worst scenario is government or private employees will play Pokemon Go instead of working.
9. Server and log-in issues.
10. It will drain your battery fast.
11. PokeStops won't load sometimes which means you'll probably lost all of the free Pokemon Items. A PokeStop is basically where you can get your desired items. In Pokemon Go, you'll have to rely on what random items will come out and not get the chance to choose what we really need from the shop.
12. It's impossible to load the game in rural areas where network data services are not strong enough.
13. Non-highly urbanized places doesn't have much PokeStops nor PokeGyms.
14. There's not much socializing going on with other players. Sometimes it's really scary to approach random people.
15. You can't train your Pokemons. It's more like searching and catching Pokemons for data collection to your Pokedex.