I charged my device all night, disconnected it at 9 in the morning. Now, 6.5 hours later the battery is at 2 bars (Notice that the switch 3->2 bars was some hours ago). This was very light use - a bit of reading, and several hours of just being on.

I'll see what happens next.
OK, at 7 hours I'm at 1 bar.
Another hour of scribbling during a talk, and the "out of power" message came up.
8 hours total.