After the drama of the last book, Death Note is never going to be the same - Volume 8 saw a massive change of events and even advanced forwards a few years. What we are now left with is a world where the legend of Kira has tremendous political influence, and a three-way rivalry between Light, Near, and Mello.
Mello is impulsive, Near is emotionally detached and calm, both desperate to outwit the other to become top dog. Light however is still obsessed with his idealistic vision of a world where he provides justice - but with three Death Notes out there and everybody wanting them, things keep getting in the way of his perfect world. It's easy to feel a bit shell-shocked after the events of volume 7, and the story feels very different now. With the bulk of this story taking place in America and plenty of new characters (including the American president) along with a major character now gone, this feels a bit messy at times. It's still great, still one of the best examples of Manga out there - but it's less neat than the previous books. Thankfully, part of the success of Death Note is the way it seems to go off on a tangent and then become neatly woven into previous events, I'm sure that now these situations have been set-up, that they will progress nicely.
The last volume saw more inclusion of the Shinigami and this continues with volume 8 - though this time there's a new Shinigami who wants his Death Note back. We get to see more of the Shinigami realm including a great insight into how they observe the human world. The way the Shinigami interact has always seemed a bit laid back and that's most evident here, I always expected their use of language to sound more archaic rather than 'street' to give them a timeless feel, but they seem to follow modern human trends and use phrases like "this sucks".
You need to take your time with this volume as there's so much going on and a web of reasons behind Light's actions. There's a definite sense that Light is becoming almost like Gollum from Lord Of The Rings, with the Death Note being his 'precious' - he has become incredibly unattached from those around him and resolutely single-minded. Seeing the way power corrupts and distorts a personality adds to the debate over the use of such a device - how can someone become the self-professed God of humanity when they are steadily losing what it is to be human?
In a nutshell: The weakest volume of the series so far occurred back when Light had lost all knowledge of being Kira and the battle of wits between him and L was absent. Maybe after volume 7 we'll always have something lacking - this remains a quality read but it does feel as though it's started to spiral out of control.