This plan is only easy in name but as with any marathon training, you will put in hard work.  This is a 16 week plan that starts light with 3-4 mile runs but then peaks at week 13 with a serious 20 miler -- to make sure your endurance is up to par for the race -- and then tapers.  This plan is good for runners who are more in the beginner range of the spectrum or seasoned racers where finishing is more important than time - however, it does include speed work so it isn't just about crossing the finish line.