I like the example NPCs for the PrCs, especially with interesting class combos. For example, reading the Green Star Adept implied a roguish-type to me with heavy skill levels and balanced caster levels, so I was surprised to see the example with a base barbarian 4/sorcerer 1. That was a neat surprise, and made me reconsider how different the characters taking the PrC might look depending on their base classes. That said, I agree with Nifft that even more variety- like monster races or templated core races, etc.- would be even better. But, I can see the need for balancing ideas with complexity to make them most useful for the most readers.
What does bug me (a LOT) is that many of the example NPCs have typos- some of them major mistakes in that they would not qualify for the PrC if corrected (skill ranks, feats, etc).