Well, OK, he doesn't work FOR me, but I did buy his book and his training plans are amazing, well-thought out, and completely customizable (in fact, he insists).
Today I had an excellent workout courtesy of his 20-week marathon plan. Instead of a ho-hum long run of 10+ miles, here's the spiel:
4 miles warmup/easy
3 miles alternating 1 minute @ 10K pace with 1 minute easy
3 miles easy
2 miles HARD
Total of 12 miles, taking about the same amount of total time as a much more leisurely and typical long run, yet working the muscles in a completely different fashion.