You can lock up the player while skipping though like 10-15 some tracks really fast, it becomes unresponsive for about 20-30 sec before the buffer for commands to clear out. sometimes if your unlucky the screen will freeze and will still play the current song, requiring a power off to fix the issue. This is on 1.03.02A firmware and done on the 32GB.
The power drain is faster if you turn on and off the player alot than compare to leaving it on. This is more evident in the larger sized flash players than the smaller ones. I also have the 8GB and the 32GB, I am assuming this is due to powering the flash. The larger the size and the longer you need to power it takes compared to the smaller one.
From what I can tell it uses the power load as a metric than the voltage to determine the what to show in the battery meter. I have notice it jump from a red level to half green in some occasions.