Oh yes it's even more insane than it is the rest of the year...but if you go after New year it's calmed down a bit...but really the atmosphere is fabulous!!
I foolishly went to Trafalgar Square one new Years' eve..well you have to do it once in your life don't you?...but OMG!! I couldn't believe there were still people in the rest of the world because it seemed like the whole planet was there..it was impossible to move. never again..but I'm glad I did it .