Looks dope and everything the gore is on some AVP shit but.. does the game even have coop option either online or offline? What about online vs play? 10 hours sounds like they knew the shit would sell either way because of the fanatics.
15 hours at most is standard for adventure types, Batman Arkum Assylum was made long because of all the collectibles then you got Assassins Creed doing the same, Marvel Ultimate Alliance is probably longer and with more replay value. Guess you would really have to be into the character to get enough from the game. Sounds like a rental to me unless you collecting GOW games.
There are things you can collect in the game to unlock certain things and there are other skins you can acquire once you beat it. Also, there is a challange mode and combat arena joint, but I haven't played those. There is no online play as the only thing you'd be able to do is play Kratos vs Kratos if they did come with something like that (or maybe two kratos' vs everything else like a horde mode.)
So if you played 1 & 2, you need to play this one. If you own 1 & 2, or the GOW collection, you need to own this one. If you aren't a fan of the series, and don't own any of the others, or haven't played the others, rent the collection and play it or either just rent this and play it. No matter what you do though, you need to play it.