The Knightsend compliation marked the end of a two-year story arc in the Batman comics, which began inKnightfall when Bane broke the Batman's back. After numerous adventures, the new Batman, Jean Paul Valley (Azbats) went over the edge and started killing, forcing Bruce Wayne to return and reclaim the mantle of the Bat. Knightsend chronicles Bruce's training under a ninja master and his final confrontation with the new Batman.
While Knightsend is good reading, this one is really for devoted Batman fans only. Like all compilations, a lot of the history is lost in various back issues and collections, so first-time readers won't feel the epic effect that Knightsend and its fellow story arcs had on the Batman saga. Also, while the story is based around the redemption of Jean Paul Valley, don't expect any in-depth literary themes or character studies, as have been in such Bat-titles like "The Killing Joke".
The story is action from start to finish, with very little else in between; in other words, it's a typical comic-book story, not the book you're going to use to convince your girlfriend why Batman comics are worth reading. Finally, and this is another fault of being a compilation, the story drags in places. Suspense is built when you read the story piece by piece, as they were originally published every two weeks or so, but when you read them in one go, you realise how some subplots were dragged out to fill up space in an issue.
Criticism aside though, Batman: Knightsend is still worth picking up, mainly because it does feature a pivotal point in the mythos. The art ranges from good to excellent; there is a minor continuity issue among the ninjas sent to attack Bruce, probably because some of the artists took creative license and altered their appearances, but this is a minor complaint. The individual dialogue boxes are excellently written, as is the norm for the folks who write the Batman comics.
If you're missing some parts to the story, or want to explore one of the most controversial story arcs in Bat-history, this is a must-have. Otherwise, I recommend picking up something more 'self-contained'.