I was skeptical of this site before buying from them, thinking that it had to be a scam to get BO3 for like 50% off. I went on reddit and saw that some other people had success with the site, so I decided to give it a try (I mean, 50% off? Wurf.) Needless to say it was really easy. Just paid with my PayPal account and got the order code. Checked the email they sent me, went to the webpage, put in my phone number and put in the code. It took me straight to the page with the CD Key and it worked beautifully.
Proof that I have the game: http://steamcommunity.com/id/RonaldHardwood
Feel free to add me and ask any questions.
Thanks cdkeys!