This is one of the best operated races in country and they pulled off a great race again this year, despite the chaos from the bombings.
Overall - The Boston Marathon is just how a race is supposed to be run. Easy to see, consistent mile markers, PRO volunteers, beautiful course, INSANE crowds. Especially running through the Wellesley College area - holy crap, the crowds are beyond loud.
The hype is real, BTW. This course is tough. They beat you up on an incessant downhill run for 17 miles and then rake you over a bunch of nasty hills, including heartbreak hill, before dumping you at the finish. Come prepared!
As for the bombings this year, my family and friends were beyond lucky to have not been near the blasts when they went off. My wife and I both got to finish and we were pretty much spared the really scary stuff. We really felt for those who were affected though.

This race is world famous for very good reason. I haven't done a road race that's executed as well and brings so much racing tradition. This, is how it's done.