I was there for the entire thing from 9 am til 4:30 pm...there was no less than 250k people. No way was there 1.5 million. But I would say 250k minimum and a high of 450k.
Yes...I was there today, too. I would say 500,000 as a guess.
The only thing is that there were definitely people coming and going when I left around 3:00, so it could very well have been much more than that as a whole.