I liked the blighter.
Its NOT a druid, its an ANTI-druid. his spell focus is necrotic, flames and such. plus using some nature-themed spells for ironic touch and reminding his origins.
Both fluff-wise and Crunch-wise its one of my favorite PrCs. hardly a game I DM don't have one as one of the minor villans. once he was the BBEG too. (along about +15 LA worth of templates but who cares?)
As for disappontment.
Mindbender.
Arcane Archer.
Dragon Deciple.
Any class that requires casting and don't GIVE casting. (there are a few)
Any class that has his entire list of abilities doable in base classes. (there are also a few of these)