Without a doubt, the battery life on the iPad is terrific! There have been a few posts from people who claim to have been able to watch things like streaming video for much longer than the 10 hour "average" use time.
But I want to take the opposite approach. For shitums (as one of us likes to say!) and giggles, I made a playlist from my library with right around 24 hours of music. It includes all 41 Mozart symphonies, all 9 Beethoven symphonies, 131 of my favorite Beatles songs, 50 of my favorite Steely Dan songs, Jethro Tull's Thick as a Brick and some filler stuff.
So here's what I want to do. Shut off the WiFi, start the playlist and put the screen to sleep. The question is, can I play the entire playlist on a single charge?