...kept going with Terry Goodkind [Edit: Miswrote this as Pratchett the first time through] for one more book.
Wizard's First Rule starts a bit slow, but is an excellent book. Stone of Tears... feels like the author is stretching a little bit to continue the series, but is otherwise also quite a good book.
Blood of the Fold felt utterly pointless, and even more strained; Temple of the Winds feels like he's just making shit up now (okay, he used one sentence out of his very first book to justify this one, but everything else felt pulled out of thin air), Soul of the Fire was back to looking for excuses to continue the books...
I gave up there the first time around, which was right around when Pillars of Creation came out.
Recently picked up Faith of the Fallen for a buck, figuring it could be entertaining.
Okay, first of all, one warning: I'm pretty sure the guy read Atlas Shrugged right before he wrote this, because I swear he retconned all his villains into Randian villains. (His heroes were already fairly close to Randian heroes, so there wasn't much stretching necessary there.) Also, the nature and content of the book.
But I'm actually considering finishing the series now. Okay, yes, there was some retcon going on there. But it's actually, on its own, a decent Randian hero story. Except his wording would have put Ayn Rand into fits in a couple of places. Ah well.
Hint to any aspiring authors out there: If you want an epic series, plan out some of the series in advance. You don't have to plan everything out, and don't write your first book as a "To Be Continued" unless you absolutely must, but put the basic structure in there to follow up on. (Non-epic series don't have to worry about this as much, not being as prone to the "I killed the big evil sorcerer now what" syndrome.)