I use it, and it is a bit of a bother, the worst of it being though that I will get anywhere from 2 to 6 "authentication" codes... which leads me to believe that they have issues. I will usually have my email open when I know I'm going to play a Ubi game, since I know they'll ask me for a code. I will then use the first code they send. By the time I'm finished logging-in and going back to my email, there is always another code, with a different number, and sometimes there are several more. Makes me wonder what kind of "bouncing" the ip packets are doing when I'm sending my initial request, or do they have issues with their servers?...
