I was very impressed by the mophie juice pack reserve and how handy of a device it was. As a student, most of the time im in class, away from an outlet or charger all together. Now since I use my iPhone 4 so much this is very inconvenient because my phone dies almost every day. But with the juice pack, i can simply reach into my backpack and pull out a roughly 40% charge for my iPhone and carry on procrastinating on my mobile device. The only downsides I can into while using the juice pack, is that it seems a little flimsy when plugged in, like it might fall out or snap the 30-pin connector off. It is also a tad bit bigger than I anticipated. With all that in mind, I still recommend the mophie juice pack to any frequent iPhone or iPod user.