I’ve never heard of this game, and I’m glad I have not. Whoever thought this was a good idea is obviously smoking.
Buying the “client” – that is, paying to register up to three characters on the Secret World servers – allows access to the basic content of the game (conservatively, 80-100 hours of gameplay before the endgame). Those who chose to subscribe will get various bonuses – €10 pocket money to spend in the virtual store, a 10% discount from virtual goods and – perhaps most importantly to the truly regular player – the Time Accelerator item – a “power hour” which doubles experience points for one hour each day.
So, buy the game, then give everyone who pays more an advantage of meaning. Oh, great.