This, coming from a WoW player since day one. I have tried just about every MMO that has been released after WoW and The Secret World has definitely renewed my faith in online gaming.
I will still retain my WoW account, I'm not leaving. But most certainly will be spending 95% of my time in TSW.
Factions: Illuminati, Templar, Dragons? Yes please. Conspiracies? Myths? Legends? Yes please.
No leveling, not classes. Your character can be whatever you want it to be. And for those that say "ANYTHING?! You mean I can be a twinkle toed ballerina who sells donuts to demons?!" .... If you want to roleplay that....sure. Go ahead.
You gain XP from killing monsters and quests, HOWEVER, the xp allows you to obtain ability points and skill points where you spend on an ability wheel and skill tree any way you want....
Want to wield a hammer and use magic? Want to use magic and use an assault rifle? Go ahead.
Anyway, just my two cents. You'll either like it or not. The questing is quite different too....those that can't think outside the WoW box will cry foul and come running back to killing 10 of this and running five maps over to get a book.