This external battery is a must to carry around during each trip. My companion was bought for a trip. Now it's my turn to go and I am not asked me the question, I bought your eyes closed! The battery is a bit long to recharge (~ 15 hours) but well worth the effort! It allows me to recharge my Galaxy S3 in 1h30 max, and 3 times without external battery runs out of juice !! It's simple, it never left my purse and allows me to charge my phone every occasion when the battery weakened a little. It also comes with a small bag, which allows me to store the external battery and its cable safely. I add my phone when it load. We can even charge 2 phones at once above (warning, this doubles the charging time), or simultaneously recharge his laptop and battery.
Do you ask more questions, it is the external battery for you!