After reading a few of the reviews I was shocked, I don't know what you've been playing but I really, really loved the game. I was easily bored by a few of the campaigns in previous Call Of Duty games but this one I found gripping, with a wide variety in the missions and best of all, key decisions you can make which COMPLETELY changes the story.
So far I've seen 2 completely different endings and I know there's more, including a secret one which changes everything. I love role-playing games too so this is a feature which really interested and impressed me. It's not an extremely long campaign, you can get through it in a day, but it's honestly great fun. There's so much to do in it!
Not to mention the side missions which enable you to control 2 squads of soldiers, a CLAW and various turrets, which was challenging but great fun.
Word of warning though: it can be quite gruesome and graphic and may not be great for the faint hearted/young.
As for multiplayer, there is more of a Modern Warfare feel (guns etc) but I still enjoy it. The league play is great for the more serious gamer and various challenges to unlock cool gun camo's is an interesting spin. It also has the 'Kill Confirmed' game mode from MW3 and 'one in the chamber' and others from Black Ops 1.
I haven't even mentioned the zombie modes yet. At first you'll probably react negatively to the change, but you'll be hooked in no time. Whether you just want to rack up a high score on Survival or piece together a story on Tranzit travelling between towns on a bus, the zombie modes will have you fixated to the screen and begging your mates to 'just have one more game'.
I could rave on and on, but I'll let you see for yourself. This is one of my favourite games for it's variety and all the game modes it has to offer.
Oh and Nine Inch Nails and Avenged Sevenfold are involved in the game. Icing on the cake.