Good! But not great.
This brings me back to the 8-bit games with a nice revamp to the graphics. However, with that being said I played on Novice and Hall of Famer and the only noticable difference I saw was the speed of the players and how much easier they seemed to "gravitate" towards your player and the ball. On Novice I returned each kick-off with a touch down no problem. On Hall of Famer I'd get tackled as soon as I caught the ball. These are both extremes
I really don't think a defensive player should be able to break through your offensive line in a second. Then when you throw the ball because he's going to murder you, he turns and runs just as fast as the ball. I know it's hard to program a flash game for football, but I don't think this is quite there yet. The passing programming is awesome and I really like the idea! Concentric circles ftw!
I gave you a 7 because this is a great start to something that could be super awesome.