As far as the entire NJO series went -
Vector Prime - Okay
Dark Tide series - Crap
Agents of Chaos series - Okay
Balance Point - Crap
Edge of Victory series - Okay
Star by Star - Good, but long.
Dark Journey - Crap
Enemy Lines series - Okay
Traitor - Good
Destiny's Way - Okay
Force Heretic series - Crap
The Final Prophecy - Good
The Unifying Force - Okay