I hear it's going to have a premium service where if you pay you'll get some benefits. However, all the services that are currently available will remain free.
To be honest, if they do go to a pay model, I hope the service will improve. The PSN network has slowed down over the last several months, and could use some performance improvements.
Back on topic -- that really sucks Pug. I managed to get a copy of it on release and the demo is awesome. However, are you sure your code doesn't work? I just checked my voucher and it clearly states that the code is valid from 11/08/09 to Launch of God of War III. Given the GoWIII isn't due out until March 2010, I'd assume that your code should still work. I would contact Playstation Network to see if you can get it sorted out. The demo is really quite fun, albeit short.
And onto God of War and God of War II. I just finished up God of War II yesterday (and its predecessor about 2 weeks ago) and the series is quite fun. My only complaint is in God of War II, you start out as powerful as you were at the end of the first, then you lose everything and have to rebuild all your magic and powers. That was kind of annoying, but once you do manage to get some of your abilities back it's all good. Also, there are some minor presentation issues. For some reason the game isn't in 5.1 audio, I'm only getting 2 channel LPCM audio from it. Also, the music is sometimes loud enough that you can't hear the narrator. And of course, the pre-recorded cinematics that use in the in-game engine haven't been redone, and they are visually inferior to the HD visuals of the game. The challenges are tough. At least for God of War. For God of War II, I'm almost done the 7 challenges (I'm on the last two), and I'll have the platinum for GoWII.