This game completetly redefined first person shooters.
Similiarly to Riddick, this game has an incredible story, which also has depth opposed to most videogames. But not only is the story intriguing, but the gameplay is pretty diverse too. While mainly you'll be shooting, the twist of the "Darkness" is the darkness itself: the darknes possesses you, and you can(partly) control it.
This makes the gameplay much "cooler" and innovative, and also, the missions, objectives, the transitional parts are pretty damn amazing.
It won't be like, alright, next mission is on the other side of the world, and within 2 seconds you spawn there... no. Take the metro. For example.
It's a blast playing: the music, the dark atmosphere, the duality of the plot(mafia vs hell), and the characters finally have "depth", they're not just 3d animations, you can feel for the main character(Jackie) or simply hate Paulie.... whatever. You will definitely remember these characters more than let's say... Wayne from Lost Planet.
I'd like to point out that the dialouge is fascinating. The writers really released a qualify work here. Every piece of dialouge could happen in real life. Brilliant work. And the developer's attention paid to the smallest details is breathetaking: full lenght movies on TV, our character's legs are VISIBLE!, people getting annoyed if you walk away from them while they're talking... etc. Also the game's tone changes halfway where you enter a place that shares similiarities with hell, and.... well, I'd rather not spoil it.
Graphically, the game blows away almost everything: it has style. Although it's mostly dark, you will always see the enviorment sourrounding you unlike in Splinter Cell Double Agent. So it's not like "well, it's nighttime, so why should you see the buildings?" Plus, the character models, the guns, the effects.... 100% nextgen. The only blowback here is the fact that there are some levels where there are occasional slowdowns, which might take away a little from the amazingness of the graphics.
On another note, sometimes the game doesn't give enough hints to the player, sometimes resulting in a painful procedure to find the next thing to do. For example, in the beginning, you have to go to Chinatown. So you take the metro... but if you don't pay attention, it'll take you to another place, and you get off, and you wonder... what the hell am I supposed to do? Of course, these puzzles can be figured out within 5 minutes, but sometimes they really hurt the experience. Being rigged up with the Darkness, and with the ability to summon 4 different darklings, and you're looking for a switch for example? Blah!
Overall, this game is a MUST HAVE for every FPS fan. It's not another run and gun game, this one has everything it should: a compelling plot, an amazing character, amazing graphics, physics...
While the singleplayer is "only 8 hours", that's the case with most games anyway, plus, I guarantee: these 8 hours are AMAZING. So I'd rather have an amazing 8 hours than 16 hours which has 8 hours of boredom. This videogame has successfully set the new standards for the upcoming games.
This IS NextGen!
(Note: I didn't get the chance to try the multiplayer, but from what I hear, the meat of the game is in it's single player campaign)
Update. Score reduced from 9.7 to 9.5 due to the new rating system. The game is also the biggest hit of the summer - even with now BioShock released. The Darkness is more epic, more fun, and it's story is more original, than BioShock's. BioShock might be twice as long, but it often feels stretched. See my BS review for more.