At first glance it seems interesting, but at 90min to charge one pack i'm not sure of it's practical value.
IMHO a portable charging station 'should' allow you to fly reasonably continuously - ie if you have 3 or 4 packs, by the time you've used the fourth one, the first will be charged and ready to go again.
If it took 20-30mins to charge a pack, I'd be more tempted to buy it.