Take it for what it is.
A Treyarch game, and their usual standards.
40% gaming, 60% unskippable cutscenes. Cuts, which I might add, blind you with constant flashing lights and numbers. They serve one use - hiding the game - they're used so you don't actually see one transition from one level to another - they're basically there to fulfill the same use as a big puff of smoke a wizard uses to hide transitions from one part of his trick to the other. And they do it badly.
An awful plot. The orrigional draft, (I saw in July) was so much better. Longer, more exciting, spanning numerous Cold War eras. US & UK missions
The only reason I'd finish the campaign is if you want to play as JKF, Nixon, Castro and MacNamara in the Pentagon zombie map. And even then, there is a way to get it without enduring the story. Or, complete the campaign if you're one of those (odd) individuals who feels the need to get ever achievement/trophey in a game.
Voice acting is bad, hilariously bad at times. Apart from Pentagon Zombies, where the voicing is excellent.
Visuals change widely from worse than CoD 4 to only just better than MW2 ( when MW2 is on low graphics settings)
One or two parts - when you're holding a knife in 'Nam, looks great. The rest of it, not so much.
Zombies and Multiplayer is where this game excells. (Except there are one or two bugs with multiplayer)
The Enfield is a near perfect model of the XL64 (and before someone complains about the weird rear-iron sight it has in game, remember, the real steel XL64 and XL70E3 L85 prototypes only ever had SUSATs and a folding fore-sight) There are, as Dave pointed out, some huge flaws (lets not forget time-traveling AUG A2s, M203s on M14s...).
The ability to pick and choose what attatchments and camos you get is very useful - rather than the previous - use X, Y times to unlock Z.
So - is this game good? Not really. Especially for £45. Not even nearly worth the price tag. Which is why I got mine for £25, and picked up Halo reach at the same time.
Its an average game. Mulitplayer is ok, but once the bugs (mainly joining games) is fixed, it isn't great.
I'd give it 5/10