The game is simply great. According to my Steam stats I used about 29 hours to complete the game (although I played mostly the non-lethal way which clocked in a couple of extra hours) so there is indeed a decent amount of game time in store. I really like the first game in the series and soon felt that I was back in that world when playing this game. There is clearly a very similar feeling and mood to it. There are of course more thorough reviews of the game out there and I am not going go the whole 9 yards to review it but I will say that if you liked the first game you will probably like this one too.
The collector's edition is a sweet package: you get the Adam Jensen figure with detachable hands and arm blades. I find the figure top notch quality and with the props (an assault rifle and the changeable hands) it is a cool item. The soundtrack included in the bonus disc along with the making of etc is a good companion to the game. There is also a 40-page artbook included but that is a bit of a let down in comparison to artbooks in the Bioshock 2 collector's edition and Crysis Nanosuit edition since it is approximately an A5-sized "book" but still it has some sweet images in it. You also get some in-game items with the collector's edition which are ok but nothing too special unless you are keen on those kinds of extra swag.
Delivery was fast. It arrived a couple of days later than the publishing date since it came from the UK or Germany to Finland but that is totally a OK since I am not really one of those people who has to have it the moment it is available.
Also the package itself it absolutely awesome. It is compeltely black and golden without any other "interference" on it. And it is numbered as well. Mine is 6480th out of 20 000.
So, if you have the chance to pick this up and you are a fan of the series, do yourself the favor and pick it up.