The fine print says that your "service" begins the moment you click the Activate button but that it takes 1-2 weeks to ship the device.
That's 2-weeks of wasted service. »
I don't see that it's MFi certified though, so starting tomorrow with iOS 7, you'll get a notification warning every time you try to use it with your iPhone/iPad.
If that's ok with you then there are much cheaper versions ($4) all over places like DealExtreme. »