The Pillars of the Earth is packed with dynamic characters who evolve over the course of fifty years during the civil war between King Stephen and Empress Matilda (Maud). Follett expertly weaves the historical facts into the narrative of the story, often including his characters in pivotal moments--such as Philip's role in the aftermath of the assassination of Thomas Becket.
This story is one of raw determination. All of the characters' motivations become apparent as the story progresses, and we see that they are utterly determined to achieve their goals. The protagonists succeed largely through wit and the innate distrust that the antagonists have for each other (the problem with being a traitor once is that you'll always be suspected of betrayal ever after). The shifting allegiances and characters' opinions of each other are quite realistic; the lifetime that the book covers allows Follett considerable character development. Not all of the protagonists like each other throughout the course of the story; their feelings change as the situation develops.
It really gets good after Part Two (these are long chapters and even longer parts--not that I'm complaining). With Bishop Waleran and William of Hamleigh set up as the main antagonists, it becomes a tug o' war game between the two sides, each wanting a cathedral and the prestige that comes with it. Follett portrays the antagonists as terrible men, with Waleran a self-serving servant of God and William an irredeemable sociopath. In contrast, the myriad protagonists are more dynamic in their actions. Everyone, from Prior Philip to Jack to Aliena, has flaws and makes mistakes that allow the antagonists temporary victories.
I found the rhythm of the book somewhat predictable; the pacing is probably the most ordinary thing about this story. Every so often, the antagonists would implement a scheme that causes a setback for the protagonists, who would have to find a clever way to succeed in the face of adversity. Rinse and repeat. This doesn't change, so I just ignored it and instead focused on the characters and relationships.
The relationship between Jack and Aliena annoys me, mostly because of Follett's portrayal. Their love develops very well, but then toward the end of the book, Aliena temporarily considers leaving Jack, because they are forced to live apart until the Church annuls her marriage to Alfred. At this point, I found Aliena's behaviour unrealistic. However, that may just be because I didn't live through the last fifteen years like she did. One of the disadvantages of the scope of the story is that the time jumps cause a bit of disorientation for the reader: the characters will have developed, sometimes in unanticipated ways, and we'll have to adjust before we feel comfortable again.
I could have done with a little less description of architecture, but I gather that this was one of Follett's primary motivations for writing the book. In that case, I suppose it was a good thing. The Pillars of the Earth is a worthy book to read with exactly the elements required for a great story. At times it can be slow or predictable, but in general I would recommend it to anyone with interest in historical fiction.