I love love love this unit, and make sure to bring it with me whenever I know I'm going to be out and about for the day, and my phone is not going to survive.  It's absolutely essential on plane flights, long days at the beach, etc. I cannot recommend this or some other type of external charging highly enough.  It's hard to be without your phone, so having this unit is a no brainer.  You can plug it in and put it in your pocket.  Easy