I played the demo of Metal Gear Solid: Peace Walker last night. It was very good. I am really looking forward to that game now. The controls have been vastly improved over MGS: Portable Ops, and it looks like a good, linear MGS game, which is more what I'm looking for than what Portable Ops was. Portable Ops was good, I just don't have the time necessary to invest into it.
One thing that really excites me is that they brought Ashley Wood on board again to do the art for the cutscenes. I absolutely love Ashley Wood's art, and that was a wonderful surprise during the demo.
I will be purchasing Peace Walker when it is released in 2010.