I like Pfitzinger but find his mid-week workouts a little tame & try to get in a little more volume. The structure and progression in terms of mileage and long runs is great. The medium long runs are good. I play with that sort of a structure and sub in some NAZ looking workouts. I also think he has too many long runs where you're not doing anything pace specific so I'll change that too.
16 weeks is a long time. 1st 4 weeks should include some VO2 max stuff. Then the meat of marathon training is from 12 weeks to 2 weeks. Make a calendar. Plan out the mileage goals (building, down weeks, peak), the mid-week workouts, and the long runs. Plug in the long tempos. Plug in mid-week threshold sessions. I like to get in 15k-20k of work in peak marathon training versus Pfitz stopping in the 5-7 mile range.