Personally I think they both go hand in hand. You can't have great game play without great graphics and you can't have great graphics without great game play.
Graphics make the player feel more immersed in their overall experience. If the visuals are aesthetically pleasing, then you can have a blast playing. However if the visuals are awful, your experience will be a little dry because you are looking at something that is not aesthetically pleasing.
Overall you can't have one without the other. I try and replay the old games that I loved back in the PS2 days, Spider-Man 2 or God of War. But, because the graphics aren't what we are used to now, it’s hard to commit playing them for more than half an hour.
I think this game definitely has the potential to look great. In terms of visuals though, I’m not expecting this game to look like something seen on the Playstation 3 hardware.