Course is very flat except for one hill that you do at mile 1.5 and again at 23.5, and a bridge at mile 10 (new this year). I have found it 4-5 mins faster than Boston. 5-7 is a nice cruise through West Side residential areas. 9-12 is pretty cool coming back into the city. Worst part is miles 12 to 16; the half marathon runners turn off at about 12.2, suddenly it can get very lonely and the next four miles are boring and utterly devoid of spectators. 16-19 are sweet, gentle downhill in a park. 19 - 23 is often a wind tunnel, 2 years ago it was 25-30 mph in the face. If you are running a decent pace (probably anywhere under 3:10), you can be all alone out there.