yup, almost a must have, but like Venom said COD4 is still king in my book. It has some stuff that is better, like more hardcore modes. It is far from being revolutionary tho, as it is basically cod4 with a different skin.
I think probably that it being essentially the same as cod4 is why they didnt call it cod5.
I still got it, I still play it, I still love it almost as much as cod4.