Zachary Taylor's biography nearly did me in. Since Taylor's personal papers were burned by Union troops during the Civil War, the biographer is forced to focus mostly on military records. After 100 pages of descriptions of the various forts Taylor commanded, I was climbing the walls. The payoff was a Presidency that lasted all of 16 months and was pretty much horrible.
Fillmore's biography has been a welcome relief. For one thing, Fillmore was not a slaveholder. It's been a long time since the previous one, John Quincy Adams. (Van Buren owned a couple of slaves early in his life, so he doesn't fully count.)
For another, Fillmore was from New York and it's been an interesting review of political maneuverings in the state, as well as a good history of the rise and fall of the Whig Party.
Fillmore seems to have been unfairly maligned by history. He was actually quite an impressive man in his early career and seems to have been a reluctant VP candidate with Taylor. His place in history seems to have been determined mostly by the terrible picture painted of him by Thurlow Weed, the head of the New York State Whig machine.
Next up is Franklin Pierce, number 14, and he represents a milestone in the reading program. When I finish his bio, I will be 1/3 of the way through the U.S. Presidents. (42 men have held the office, but Grover Cleveland is counted twice as he had the only non-consecutive terms, hence GWB is the 43rd President.)
Pierce, then Buchanan and, finally, greatness. After reading about mediocre to awful Presidents for so long, it will be exciting to read about Lincoln.