The London Marathon was an amazing experience!! The crowds!! The people! It was jammed with cheers throughout the whole race. So much to see and experience that you never got bored once! Worth the trip! For 2018, it was hot. Hotter than you anticipated I think for all. As an American, there was little things too that were different than when running in the states. Such as the water was given in small flip top water bottles, not cups. Only one station on the course was cups. The flip top bottles were nice though! I didn’t try their version of Gatorade (Lucozade) and stuck to my GU gels. My only advice to organizers would be to make the water station signs more prominent (they were white branded with the water company logo) but they got easily overlooked versus a bright color. And the signage for any medical tent was awful. Thankfully no need for me to use them, but I really didn’t see any med tent signage. Be prepared for the first miles being super crowded even if you are up in front. Slower first miles. Be careful with center street medians too. I saw one man fall hard because he tripped the center street dividers which were somewhat frequent on the streets. The race did a nice job of painting a dotted blue line which was the official course route for elites to follow and that helped me a lot to look down and know which side of the road I need to follow. All in all, a fun, high energy race, and a great experience. Not necessarily a PR race though due to the crowds.