L.....my husband plays this game and I feel it is somewhat addictive. Some days it is like pulling teeth to get him off the game to come help me with household things. We recently had a fight over it and he has gotten better. We made an agreement that he would only play after the baby was down for the night. Some nights he would play the game until 3 or 4 am (on weekends). It became a problem. But like I said he is getting better now.
I recently saw an episode of Dr. Phil about people addicted to online games and World Of Warcraft was one of the games he discussed. I just think there are so many better things an 8 year old could be doing. Like playing outside, or playing with his dad (and I don't mean online). I would be afraid that he would get addicted to the game. Good luck!