I have been a long time player as well and can vouch for the pro's of this game. The game encourages team play and because the real world is the map of the game world it gets you off the couch and meet new people.
One thing I like about the game too is it is actively developed meaning new changes are always coming which keeps the game interesting.
Another advantage is because 'portals' are based on real world points of interest, its a great game to play when travelling because you literally discover neat places you may not know about otherwise.
Lastly, if you decide to play, join the resistance
Currently the enlighten is kicking our butt, its much more fun being part of the underdog.