Love the concept. Looks like its perfect to take on travel (when a day's charge is never enough). Not sure I love the harsh corners though. I think I like this form factor a bit better: http://www.tylt.com/energi/
Important note: the new iPhone 6 & 6+ support 2.1 amp charging (offered by larger iPad cube) vs. the stock 1amp charging cube. This means if you use a 2.1amp charging cube, it can charge much, much faster. Currently (no pun intended) my iPhone 6 is charging twice as fast. nnThe Bolt is 1amp. So you may want to look for 2.1amp solution. nn
I had a belkin version of this for my iPhone4, where the backup was also removable and plugged into the phone. This looks like the best replacement for that.