Its challenging. Don't let any comments about beautiful scenery fool you: if you underestimate this course, it will chew you up and spit you out. Its rocky, so choose your footwear carefully. If you are running anything beyond the 21km mark, make sure your shoes are well cushioned or provide a stone guard underfoot.
I am 6'1" and 190lbs and I don't step lightly. So, by mile 15, the ball of my feet were taking a beating.
Also, aid stations provide water and ice only. Be smart about your fueling --I wasn't.