I think it was a shame not to run past the Tower of London, cobbles or not. It's one of the great landmarks on the course. I found it very confusing going the wrong way round docklands and as for having people running on the left hand side of the road on the two-way bit, very peculiar. Perhaps I know the old course too well.
Yes, there were narrow bits at times. Not sure if this was due to the crowds sneaking forwards though as they only seemed to be held back by tape in places.
I thought the crowds were very good.