Airport has charging stations, but it's hard to use when people are hogging.  The place like a theme park doesn't provide a convenient way to charge with AC nor can't wait around.  iTorch provides a convenient way to charge and has enough capacity (5200mAh) to support most devices to last more than a day.  This is a better solution than buying an extra battery since this will work regardless of the models.  Besides, replacing a battery is a lot of hassle.