I have the little AA charger and have been unimpressed because it was so expensive for what it does. I was also a bit annoyed that they didn't send along a AAA adaptor like most other rechargeable sets include. And they're not easy to find for this unit. I was going to go for the larger teardrop unit, but am rethinking that, especially since I found an inverter that can be plugged into a car battery charger and has both USB and regular household plug.
http://www.goalzero.com/shop/p/79/Guide-10-Plus-Adventure-Kit/1:4/
I too use an inverter that allows for way faster recharging or power source for things like laptops.
Solar products are for backup and do recharge very slow, compared to 120v power sources.
If I run out of gas or don’t have electric in my house then at least I have the solar recharge system.