I did this as my first marathon in 2010, it is a great race well organised with a very friendly atmosphere. The overall profile is down hill and undulating, as referenced above the most challenging climb comes around mile 18, happily thereafter its pretty much down hill / flat to the finish.
A couple of suggestions from me:
Try and resist the natural urge to run the initial down hill sections too quick you may as I did set a new 1/2 marathon PB but find the next 13 miles a tad tougher than it ought to be!
Train both for uphill and downhill the overall profile is downhill and your quads will take a battering. A common way to train the downhill is to alternate running fast up, slow down / fast down, slow up on a hill of decent gradient around a quarter mile in length.
Take a bin liner and some old race tops for layering / water protection at the start and discard as necessary at the water stations. Nervous of the October weather I wore full length tights and long sleeved top and was freezing at the start, perfect for 3-4 miles and then absolutely boiling for the next 22 miles.
I seem to recall in 2010 it felt like there were many sports drink stations and fewer plain water, I carried a camelback with sports drink in it and remember craving plain water.
If you are planning on eating out in the town the night before google the restaurants and reserve a table in advance they were packed in particular of course the Italian eateries.
Finally ENJOY, there are few better places to run a road marathon with a fantastic atmosphere in the town before and after.