I never would have thought, in a million years, that I'd be saying this about a John Carmack game. I'd go so far as to say that if he was to read my "review" of his game, he'd probably commit sepuku.
This game is absolutely fabulous for pick-up and play purposes consistent with an older; more family-oriented demographic (like being a dad.) The storyline covers some well worn ground, but you can excuse it because the character animation and all of the art direction in general is simply fabulous.
Game mechanics make combat thrilling, but not overly challenging for someone that plays maybe 5 hours of games a week. Graphics troubles aside (which have been resolved in almost all cases) there simply aren't any negatives to this game from a playability standpoint.
I do have a few criticisms of the metagame experience; but it seems like a lot of developers are running into trouble trying to use Flash (or similar tools) to build their UI and HUD. The menus don't really feel as well thought out as the details in the rest of the game world; and you'll find yourself wanting to use them less-and less as you get deeper into the game so you can fully immerse yourself in the magical kingdom that is Rage.
Looking for a casual game that challenges you but doesn't require countless hours in front of the screen? Look no further than RAGE.