What's the point of Princess cruises

P&O vs Princess cruises.........
It's an incendiary question and I'm sure there will be hordes of Princess cruise fans baying for my my blood out there by the time they finish reading this.
Stick with me for a minute though and let me know what you think before lynching me; I think I've got a fair point here, (he says).
First though a bit of background on Princess cruises might help anyone that hasn't cruised with them before.