The game is a free download and has no ads, which we appreciate. The game's earnings are all through in-app purchases of the items mentioned above. You get most of these at Pokestops and the ones you don't - such as a Lure module that lures Pokemon to Pokestops - are not essential to playing the game. We think the developers have implemented in-app purchases tastefully. You can play the game without spending anything.
Pokemon Go is a well-designed app as far as interface is concerned, but what is the point of a beautiful app that freezes and crashes all the time? It will also drain your data pack and battery life, and the battery saver mode in the game is not much help. The game isn't available officially but people have and will install it anyway and be greeted with an inferior experience. The game is very enjoyable but playing it in India is not.
