The speakers are powered by a single AA battery so it does not drain the iPod's power. What I liked most about it is the design, especially its simplicity and size relative to the iPod. Just plug it into the headphone jack on the iPod and you are good to go. Since the plug is standard, it will actually fit ANY device with a mini headphone jack (CD player, other MP3 players, tape recorder...etc.
I was surprised by the reasonably good stereo separation. It does a good job handling most types of music if the volume is moderate. It is perfect for audio books files. This little unit does have some flaws. We found the distortion quite high and the sound too thin for bass heavy music. However, due to its size that should not come as a surprise. If you find one on sale... it's worth a try.