We went in the early afternoon, there wasn't a line anywhere, so I'm not sure if there was a need to even purchase this. The museum was interesting and modern and a good place to get exposed to history without the hurried pace of a tour guide, if thats what you prefer.
This may have been more helpful in high tourist season. There weren't lines. The museum is terrific we saw it after a Segway tour around the Acropolis, the day before we actually went up to the Acropolis, and I think we really understood what we were seeing. Lunch at the museum was good as well.