I enjoyed the DS9 Companion and it worth the money I paid for it. The same could be said for the TNG Companion and the TOS Companion. All three give a wealth of behind the scenes looks. I especially enjoy the bits about what bits of the episode was left out or storylines that were contemplated but not adpoted. But the DS9 Companion was the superior verison, it gave a lot more info than the TNG or TOS version well its also about three times the size of the other two...but then it had a better story to tell...in the end
Arise, arise, Riders of Theoden!
Fell deed awake: fire and slaughter!
Spear shall be shaken, shields be splintered,
a sword-day, a red-day, ere the sun rises!
Ride now, ride now! Ride to Gondor!
Theoden King: The Return of the King