PSN works like gaming on ur pc, U dont pay for anything other than the game for it to work properly. M$ charges u a big fee for what is just a tarted up server browser for internet based games, Which is even more of a ripoff now that most games use p2p/ad-hoc instead of dedicated servers. Unlike free PSN lol, Thats why u get 32-256 player matches on PSN while the biggest i think u get on LIVE is 8-16 players, thats ruined by host advantage all the time too.
Even most of the media content available on LIVE gets sent straight from private internet servers and dont even get routed thru LIVE servers at all.
All u get extra if u pay for PSN+ is free online storage for ur saves, early accesss to betas n free PS1 and arcade games...