Me personally: I have only come up with one liability with the Mophie juice pack Boost, and that is that the plug will sometimes fall out. Outside of that fault, Mophie has really designed a great battery pack. I love it and would recommend it to anyone considering a portable battery pack. This device can be bought here: Mophie Boost or on Amazon.
I am working on my photo skills, sorry for the flash problems. Thanks for reading!