As Cassandra Nova actively attacks the Shi'ar Empire by posing as Professor X, her more subtle attack on the X-Men almost breaks then mentally as well as physically.
This volume continues building on the foundation that the first volume set, with Cassandra Nova being a hidden threat. Hidden, because the X-Men thought they had dealt with her in the previous volume. She instead jumped into Professor Xaviers body, and put his mind in her old, dying body. She then proceeds to take over Lilandra, Empress of the Shi'ar, infiltrating via the relationship that Lilandra and Xavier have. Meanwhile, back on Earth, the X-Men discover that the flu that they all have are due to microscopic sentinels that Cassandra released prior to her leaving the planet.
So much going on in this volume, and Grant Morrison juggles it all expertly. The pacing, the characterization, the plot in general, its all masterful and told masterfully by Morrison as he rips through the X-Men's life with all sorts of new threats. I loved how he had Jean step up to be the leader of the school, and showed off her badassery. Also he manages to make Cassandra a legitimate threat by having her do and not have her just say. In other words, she enacts her plans first instead of giving some big speech about what she's about to do. She really does feel like an unstoppable force at times.
The one thing that is a bit of a letdown in this volume is the art at times. Quietly takes some issues off and lets some fill in artists take over, and... it's not the best. A lot of the art seems rushed and/or messy. It didn't take away from my enjoyment because the plot was so strong, but its definitely noticeable.
Overall, this run of the X-Men has an energy to it that just propels you to read further and further. I think Marvel did a really smart thing by hiring Morrison as he delivers on his promise to "shake things up" with the team. Onwards to volume 3!