Here to clarify few things:
1) The token generates a new password each time your press the button, that password will be valid for the next 30 seconds time (actually if you press the button again during the next 30 seconds the same password will come up)
2) You don't need to memorize the password used to register it, it's used only at that time to confirm that the serial number that your are typing is actually correct.
3) When you log in your account you have to write BOTH your Square-Enix account password and the one time password from your token, and you have to do it within the 30 seconds after pressing the button.
As far as I can tell the tokens with the CE are working just fine, I registered 4 accounts yesterday and each of them logged several times when I was tweaking the settings and never had a single issue.
Edited, Sep 23rd 2010 4:14am by kenage
Mostly... it's not generating a number when you push the button, the button simply turns the LCD display on. "Under the hood" is the code generator, and it's running 24/7 generating a new number every 30 seconds.
So, you can be unfortunate enough to press the button, get the number, but by the time you type it in it has already expired and gone onto the next number.
I haven't had any issues with mine in FFXIV, I've used it a few tiems. I had the same thing in WoW and used it for a couple years without issue also. Just don't even think about it until you've got your username and password already entered, then press the button and type it in quickly, don't wait around.
I supose a potential problem could be if you typed in the serial number on the back wrong, but I thought the registration page asked for the random number when registering so it could verrify that your serial number is lining up with the random number like it's supose to.