Volume 23 of Bleach is strong continuation of the Arrancar arc. It starts off with Ichigo recovering from the beating him and his friends received at the hands of the arrancar, Ulquiorra (a personal favorite character) and Yammy. Everyone is looking inside themselves trying to figure out how they are going to deal with the coming threat.
Rukia arrives, and in her own "special" way manages to cheer up and refocus Ichigo. Her return also has an effect on Orihime. We get to spend some more time with the Ichigo's friends and associates in school and around town. And begin to notice that alot more people are becoming spiritually aware. This is gaining the arrancar's attention.
The arrancar are Hollows who have removed their masks for more power, Soul Reaper power. Though the difference in strength before has been minimal, with Aizen's help and the orb's properties, these new arrancar are strong enough to battle Soul Reaper captains. The arrancar are no longer an anomaly, they are a force.
This fact is made abundantly clear during this volume as the reinforcements from Soul Society, Renji, Rukia and others are almost immediately matched against a force of arrancar led by Grimmjow, a very powerful opponent. The volume finishes with this match up. Its a good classic example of Bleach's action, Hollow vs Soul Reaper,with their unique abilities and ideals showcased. One the highlights is seeing Rukia in action (finally!) & she does not disappoint.
Overall, this volume is a good mix of the comedy and character development that start the volume and the vicious hardcore battles that finish it. I recommend it as a good continuation of a very strong series.