This brought the total playable "commanders" to 9, each with unique voice lines, cinematic introductions, and playstyles. That level of asymmetry in 2003 was revolutionary.
Zero Hour was praised for providing enough content to feel like a standalone sequel: Review - Command & Conquer: Generals ~ Zero Hour command conquer general zero hour
The voice acting is cheesy, the cutscenes are live-action with questionable acting, but the atmosphere is 100% pure RTS gold. This brought the total playable "commanders" to 9,