Pokemon Go can be enjoyed anywhere. However, there are definitely disparities between urban and rural area. This page shows the differences examined in Japan.
For Pokemon Go gamers, where they are living in is important for getting items. gainnng XP, capturing wild Pokemon, and having gym battles, because the number of PokeStops, wild Pokemon, and gyms are different between urban and rural areas. Here are the screenshots showing the disparities in Japan.
Urban areas in Japan
Yamanote Line
There are so many PokeStops around Yamanote line, one of the most important loop lines in Tokyo, Japan.
Shibuya
Shibuya station, one of Tokyo's busiest railway stations, placed a lot of PokeStops around of it self. That means Pokemon Go player can gain much XP and get whole bunch of useful items.
Akihabara
If you open Pokemon Go in Akihabara, one of the biggest shoping districts for video games, anime, and manga, you may not be able to back to home due to many of PokeStops. You may not have enough time to visit all the PokeStops.
Rural areas in Japan
In rural area of Japan, no PokeStops can be found. That means you cannot gain XP to increase trainer level and obtain Pokeball to capture Pokemon.
It is obvious that there are few PokeStops relative to urban area. Additionally, you cannot see gyms and have gym battles. Some people says Pokemon Go is for only urban people.
You do not have to be worried about that getting Pokeballs in rural areas, because there are no wild Pokemon to use Pokeballs.