I played the game for a while but have stopped now except to check once in a long. I figured the end game, other than trying to catch them all, is battling and controlling gyms. I guessed that as the most valuable game currency (akin to the "magic stones" PAD) are given from controlling a gym for a set amount of time. However, I don't like the battle mechanics as it is mostly just rapid tapping on your Pokemon. It definitely does not have the depth of the handheld Pokemon Games are even competitive and have world tournaments. The game has made me interested in Pokemon again though and I went back to try to complete Pokemon White for the DS.
I might pick up the game more if they improve the battling system but I highly doubt so. Here are some tips and links I picked up while researching about the game. I don't use any illegal methods like apps to tell you spawn locations or location spoofers: