Just finished playing the demo and all I can say is that the $5 price on Amazon would of been a steal. It took me a few minutes to get used the controls and feel of the game, but once I did, I had a blast. Unfortunately, I couldn't play the game online (demo servers are either full or unavailable apparently), so this impression is coming from playing single player against the bots!
I'll keep an eye out on Amazon throughout the day to see if they restock. Here's hoping soon.