If your the type of player who likes to try and "catch em all" then this is for you, with 999 Pokemon Storage you don't need to worry about space, this is also true if you like to collect shiny's and event's and the game also helps you with finishing your Pokedex if you havn't already, the game also allows you to trade for a number of Pokemon that are classed as events which include Pikachu, Eevee, Manaphy and Mew, if any of these things seem of use/intrest to you, or you would just like to sit back and watch your Pokemon having fun then get it, if you are just interested in competative battling or none of the above matter to you, then there is no reason to bother with this.