Just finished my first playthrough. Going for a second one right now!
Graphics on this game is not spectacular, i.e Crysis, but it has its own distinct flavour. Environments are dyed in black and gold, giving it a very futuristic feel. Might be a bit too much though as it gives the game a very sterile feel. Though some big neon signs in detroit and hengsha provides some contrast.
Gameplay is fantastic. There are many ways to complete a level through the use of air vents, fire escapes, hacking doors, "stealthing" from cover to cover, and of course, just mowing down enemies with your tricked out heavy rifle. That being said, the game rewards you more for non lethal takedowns, giving you more experience points towards upgrading your augmentations.
But although the stealth approach pays off more over the course of the game, the boss fights are really a pain in the ass. They force you to go the shooter route, with stealth being next to useless during these encounters. So even if you're going the stealth route, it will definitely pay off to spend some credits on upgrading your gun with weapon mods.
Story is very interesting, touching on power, the responsibility that comes with it and human nature. It also brings you on a trip around the world, visiting vastly different locales like Hengsha Island. Hacking computers also gives you more information through emails. There is even spam mail, which I think is a nice touch.
Sidequests are also varied, not like your typical go here, fetch x number of items or kill x number of enemies. Highlights include sneaking through gang territory undetected, and snooping around a police precinct, investigating the attack. All these side quests can of course be skipped, but then you would also be missing a huge chunk of story. Though at the time of writing, there was a bug with one of the sidequests where one key enemy just disappears into the sky or into walls. Hoping they'll fix this soon in the next patch.
Overall a very good game, with a very good story.