Yup, the shooter part was really good. The world actually *looked* good, even though it is highly linear. The texture streaming was completely borked (and still is, last time I checked it). The story is like... I don't know, they just stopped and called it a day.
Sometimes I find myself restarting Rage, but I never finish it. Really a shame... This thing could have been so good.
Oh, and it didn't helped that the modding tools got released years later. At this point it was too late. Nobody had any interest in the game and engine anymore. They should have put it out right at release, then I bet we would have seen some cool projects arise.