Want a surprise? Battery life on my smartphone sucks. I'm always looking for small, simple external packs that last. For $20 the Anker Astro-Mini gets the job done!
This lipstick sized battery with a USB port takes about 2 hours to charge fully. The device offers a bit more than one full charge for an iPhone 5. Less than 1 full charge for an iPad Mini. It is simple and I rarely forget to carry it with me when traveling. Performance has been fine for approximately 50 charges. Anker also offers an 18 month "worry free" guarantee, but I haven't had any reason to contemplate needing a replacement.
You'll need your own specific cable to charge your device (unless you take Micro USB, which is included,) but thats about it. I'm happy to have it.