We were there the first week of November and it was totally crowded! Our Angel tours guide told us that in 1972, 2,000 people went through the museum in a day.
Today, in 2007, 20,000 people tour the museum each and every day.
Expect crowds. Make reservations, and buy a "skip the line" reservation...then you don't wait outside to get in. You pay a bit more, but your time is worth it!
I do recommend Angel Tours. Worth the money. Very informative, and small groups of 16 or less per guide.
You pay when you get there, so have cash ready. And Please tip!