Having run 5 of the six majors, I can say that London exceeded my expectations.

The Good:
Organization is top notch
Course is scenic and fairly level
Hydration stations well placed
Expo excellent (big pick up, speakers, etc)
Transportation to start is excellent and well directed by volunteers and tube staff
Post race is the best run I have seen from medal to bag pick up. Smooth and easy.
Can't say enough about the UK fans. As an American, we get good race crowds but these folks were amazing and supportive.
The finish scenery coming around Parliament/Big Ben to Buckingham Palace turning right to finish was as spectacular as Boston or Berlin's iconic finishes.

Areas of improvement:
Full bottles continue to be an issue, not just with waste but "rookies" still just drop bottles in road vs toss.
Walk from tube station to start areas uphill and long. Consider shuttles?
Can't change it but don't expect a PR due to crowding. I was corral 2 so started up front and I still had bottlenecks after 5k. Slowed and had to make up time. Nothing to do about it but to expect it.

Overall, an amazing event I would do again. If you are traveling from the US (or anywhere with a time change over 5 hours) be sure to arrive by Wednesday at the latest.

Well done, London and Abbott WMM. This race shines.

The theme shouldn't be the weather since its out of the race control, but its an unavoidable topic. It rained. A lot. For any runner who has been doing this a while, we have all ran in bad weather. The race could have started at 8am sharp and it did not. I was in front corrals and it was wet and cold and would have been nice to skip a bit of the talking and get to running. Pointing out that runners should be careful with all the toss-out rain gear was smart. Avoiding painted lines and manholes would have been good advice for newbies. Anyway, out of race control so moving on!

As far as the start, the same issues exist for all large races (bathroom lines) so short of multiplying the amount of bathrooms, just get there early and watch what you drink the morning of the race. No need to pound fluids for a 10 mile run on a cool day in the morning. Hydration starts days before anyway. The bag-drop busses were not good. I stayed in a line, was told bus was full, went to another line, same thing happened and finally 30 minutes later, got one of the last stickers and bands for that bus. Someone has to let folks know the bus is filling up. I nearly was late to the corral. Large race or not, this can and should be fixed. Its a bus with a set number of spaces. Have another volunteer count off folks and set the end of line.

The race itself was awesome. I got out fast and got in a nice rhythm early with no crowds or anyone clipping my heels. I didn't use any of the water stations but they were plentiful and well staffed (bless them for standing out there!!). I found the finish area to be great, but if it got crowded I can see the narrow street to be an issue. Personally, it was smooth and although no real sign to go grab a medal and a snack, it was easy to spot with the tents. Getting out of the race area was a different story (I stayed at the Courtyard on site at finish) and it was tough getting out. Otherwise, it was a very "Chicago Marathon -like" course and nicely set up to run fast and comfortable.

Race gets an "A-" from me and looking forward to next year.

I have run some of the other Marathon Majors and Chicago leads the pack in terms of organization, volunteers, crowds, security and course. Similar to Berlin, this is a fast course. The lack of hills actually is a negative as a fast runner needs to have other muscles activated during a race and this one beats the same muscles up. Most will think its a dream course, but flat is not always ideal. New runners will feel it tomorrow and understand what I am saying! Otherwise, a great race experience in a terrific city.