I'm a longtime Fallout fan, and a longtime rpg fan, and while I was nervous and skeptical of this release at first, I can say I am VERY pleased with it.
-Layout: Better than most more contemporary rpgs, the layout is fairly clean. Most information you need is in appropriate places, and not scattered ALL over the place. (Side note, many of my favorite rpgs have horrible layouts, and I still love them, but when one DOES have a good layout, it's just that much better.)
-System: The 2d20 system is pretty easy to grasp; small dice pools of d20's (2-5 dice) with a roll low target (equal to or under stat+skill for a success), more successes, the better you do, extra action points, etc. I am not a huge fan of the 'need' for the unique dice for the combat dice, but unlike Fantasy Flight/Edge's Genesys (again, love the hell out of Genesys,) managing without the special dice is MUCH easier, since it's just d6's with special faces.
-Setting: Already a well established setting, the book/game does a pretty good job of explaining the world of Fallout, the major players pre-war, and giving a brief explanation of the anticipated setting of the book (The Commonwealth) while still mentioning expanded portions of the known world (NCR, Appalachia, New Vegas,) but also doesn't give away tooooo much. It threads existing lore into a new medium pretty fantastically, gives me solid hope for the future of the rpg releases.
-Art/Design: Here's where I was blown away. The art is top notch, and the design behind the layout felt VERY Fallout. Gorgeous and easy to read, a truly well put-together piece.
-Overall: If you love a good blend of crunch and fluff, an easy to learn system with lots of options, or just Fallout in general, it's a fantastic book/game to pick up! I really hope for books that give material from other games, I'd really like That Gun, from Fallout 2/New Vegas, or the Scorched from 76 introduced. Maybe even working with Bethesda to come up with a new region for the rpg to cover. I know I've been brainstorming my local area for a Fallout game!