The Siege was a great book - considering it was outdated rather quickly. How so? Well, when it was written there were only five episodes of Deep Space Nine that had aired. Author Peter David really had to "wing" this one as he wrote. Despite this, he did a very good job! Most of the characters - especially Odo and Quark, were right on target. Whether Meta - the mysterious shapeshifter killer that shows up - was a Founder or not - most likely not - it does not take away anything from this story. He was extremely well written - and slightly morbid. Be warned.
As briefly alluded to, the plot is simple - a serial killer is on the loose, and he must be caught. Things get sticky for Commander Sisko as two war ships from two different races - one is a Cardassian led by Gul Dukat, the other is a race of religious fanatics - expect justice as two of their people were killed. Sisko is effectively caught in the middle and must rely on Odo to catch the killer. As we read, this is no ordinary killer.
The typical Peter David humor adds another dimension to The Siege that makes it very much worth your while. You don't have to have much Star Trek knowledge to read this story - it is not very ambitious like some of David's other works - i.e. Q-Squared or Imzadi.
The ending was not predictable and extremely exciting!