Those who know more about this practice say there are some significant disadvantages to sharing, besides being unlawful.
1) The credit card account information, including online wallet are available to the sharee.
2) Sharing may cause the original Purchaser to lose the rights to the game if his/her PS3 loses data or needs to be replaced.
3) The additional 'user' has access to the account and could change the password shutting out the Original Purchaser.
4) The Original Purchaser may 'shut down' (deactivate) the game at anytime.
Gameshare is for Friends & Relatives, when you go to their house and you, yourself access your account on their machine. And, You, yourself deactivate it before leaving.