I bought this after reading countless reviews for various portable charging devices and am SO glad I did.  My husband and I were both able to keep our phones charged on a trip with 30 hours total travel time.  I was able to watch movies and my husband listened to his iPod during all 4 of our flights and 10 hours of layover in addition to the occassional extra charge needed when we were away from our hotel for long periods of time.  I also use this charger when I've been on my cell phone at my day job all day and don't have time to charge it.  I plug my phone in while it's in my purse in my locker at my evening job.  It turns itself off once my phone is charged, so there's no risk of damage to either device when left unattended.  I'm able to get my phone from no charge to full charge at least 4-5 times before I need to recharge the charger itself.