I've been dying to read this since it was first announced. I'm a big fan of the OAV and the (second half of) the TV series, and now I can see how it all began. And it doesn't disappoint!
The manga goes back to where it all started, introducing a much younger Yomiko Readman and Nenene Sumiragawa as each was just emerging into the spotlight of international Library affairs. For those that have now caught up with the TV series, you can see just how Nenene's relationship with Yomiko begins, and in terms of filling in the backstory, these 3 volumes are pure gold.
Volume 1 sets up the Library of England and the idea of Paper Masters very nicely, with good pacing and clear artwork., as well as some very capable villains (none more so than Fire Inc - damn, she's hot! ...sorry...). Yomiko herself is still every bit the ditz she is in her animated adventures, but by volume 2 we get to see her in some unusually deep torment, as her lover and mentor Donnie Nakajima is brought to the fore (touched on only briefly in the anime), making her character all the more fleshed out and sympathetic.
Other characters also make memorable entrances - the Joker of the manga is clearly more openly devious than his anime counterpart - he's an assured con-man who clearly has an agenda, and it's made clear early on that everyone around him is a pawn serving his clandestine purpose. Similarly, it's a shock to see a younger and decidedly more innocent Wendy Earhart aiding Yomiko in her second mission. You wouldn't imagine that this cute and emotionally immature girl could become the cold and ruthless killer seen in the TV series.
In fact it's debatable as to how "canon" this set of books actually is. The ending doesn't gel with the anime, and it's probably best taken as it's own continuity, which is a little annoying since so much could be relevant had the books not gone their own way.
Fans of Read or Die will adore these books - not just because they deal with characters that many of us love, but because they make great reading in their own right.