This is a real addition to the Watchmen universe, materfully bringing the graphic novel to life. This isn't just a gimic to pull in more profit on the back of the movie, and if you love the comic, I'm pretty sure you'll love this too.
I like the way the motion comic is divided into chapters on the DVD (the same chapters as in the graphic novel, of course), which helps break up the ~5 hour duration into smaller, ‘user-friendly’ chunks. The narrator does a good job as well (although his ‘female’ voices don't sound very feminine). Watching this makes me want to watch the excellent movie again too!