I hope I'm not repeating myself, but IMO there is a significant decline in quality in Zahn's post-Vision of the Future works. Survivor's Quest was still pretty good, but Outbound Flight and Allegiance were poor.

I think Zahn's strength is in portraying our heroes in the post-Return of the Jedi years, although he never really completely solves the Han Has Nothing To Do After Empire Strikes Back syndrome (HHNTDAESBS)

He also falls too much in love with his own creations (I rolled my eyes at how perfect Thrawn and Jade are portrayed in later works).

Of course these days he has to write with all the other terrible EU in mind. And the Prequel nonsense of course.