Metal Gear Solid 4 was one of the most well-written video games I have ever played. I think Hollywood should take lessons from it. And it's proof that someone should start a sophisticated and classy Oscar-like awards ceremony for video games.
Ratchet & Clank Future is a really good 3D platformer.
Saints Row 2 is probably the most creative open-world crime game ever made -- that is if you don't already have it for the 360.
Little Big Planet is freaky, stay away from it.
Resistance is so-so. Resistance 2 is pretty good, although not great.