Others say...

"Just so that you know what this is..."
This product makes an electrical connection between 4 AAA cells and the input to your iPod. This should strike many as strage, because the input to your iPod is typically less than 1.5 x 4 = 6v. It's more like 4.2 or 5 volts. I bought mine on NewEgg and realized that there's a non-refundable disclaimer somewhere, so I can't send it back, or I would. Among the side effects -- it adds a low but distinct hissing sound to the playback. It's not a huge deal because of how low it is. The other problem is more worrying -- sometimes your song gets garbled like it would if your CD or LP record would get stuck on the player. This has *NEVER* happened to me on an iPod, so it was horrifying when it did. It came back to normal the moment I unplugged the battery backup. It doesn't happen all the time, but it's enough for me to trash this piece. My iPod is not worth the experiment...

"Not as good as expected."
I purchased the TuneJuice 2 because a review I read said it would work with the iPhone. I needed it because I was flying cross country - twice. I wanted to watch movies on the plane and while waiting at the airport, and I know that the iPhone battery wouldn't last 10 hours.

When plugging in the TuneJuice 2 the iPhone states that the device was not made for the iPhone - and that I should turn in Airplane mode. Not a problem on the plane, but not desired in the airport waiting to board.

The TuneJuice 2 does not charge the iPhone - which I knew, but it was supposed to maintain the iPhone's battery level. What I found was that the device slowed the battery drain while watching movies. Also - because of the short cord, the TuneJuice made it uncomfortable to hold the iPhone during the flight. I either had to place both the phone and battery on my lap and look down - or hold both up in an unnatural position.
Finally - there was no indication anywhere of when the batteries in the case died - so halfway through the flights, the iPhone discharge quickly.

Pros - The TuneJuice 2 did help me watch movies on my iPhone during cross country flights.
Cons - No battery level indicator / Doesn't charge phone or boost the battery at all - only slows iPhone discharge rate / Uncomfortable to use.

"TuneJuice2 - No Juice"
The unit was recieved with flat batteries, no surprise. Purchased new batteries and when you plug it in it will push your battery indicator to full but two songs later the battery indicator is down and draining fast. Stay away from this device. It is absolutely useless.

"Better The Product Package Says it is!"
The package says it works for the older models, not true, it works for my 160 gb Ipod. Sure you need to charge it while there is still a power source, but all you have to do is watch for a low battery and plug it in. It is a great on the go charger!

"Great for long flights"
Works perfectly. I used it on flights to and from Russia and it was just what I needed. Just be sure to bring plenty of extra batteries - especially if you are watching videos.