The game is going to be released in about 10 hours in the US and on Friday in the EU, and if you planned on preordering I'd suggest you do it now:

http://www.greenmangaming.com/ 15% Off
Voucher: 20SUM-MERSA-VINGS 20% Off

I doubt you'll find a better deal somewhere within the next couple of months.

Reviews:

RockPaperShotgun (No spoilers)
PCGamer 94%
Joystiq 4.5/5
Ars Technica Verdict: Buy

Registers on Steam, though I've no idea if you'll get the related TF2 items if you buy it on GMG.

 

You can get it for 20$ approx here. Also I am so fucking excited to play this. Dues Ex is one of my most favourite game ever and if it's anywhere close to it like the reviews seemed to indicate,then I will be happy to waste 30+ hours playing it.