I grabbed the Heavenly Sword demo upon its release on the PSN.... and although it looked pretty and had god of war-esque button related, context sensitive action.... it was so short and I just didn't understand the combat system enough for it to really be any good. There was some cool stuff, but without any sort of explanation of how to actually use the combat system, it was pretty lame. You fight two groups of enemies after sliding down a giant rope.... I'm sure the real game will actually contain some content, but the demo was lame-o.
there's a kotaku article that pretty much repeats what I said, but in prettier words.
http://kotaku.com/gaming/too-short-for- ... 283193.php