its good for what its intended to be used for. If you can plug in your charger dont get this, if your out in the wilderness and need a way to charge your phone, i would say this i a good way.
I took my girlfriend to disney land about a year ago, and had my pre. Used it some, but it was the pre and died quickly anyway. Regardless i had left the solio charger on her dash all day. And by the time we got back it was fully charged. (we're talking 14 hours here)
On the way back from Disney land, its about an 1.5-2 hour dive, there was an accident, and traffic was being diverted. Pre was dead and we didnt know how to get back using the other route. Longer story short, i plugged that bad boy in. we pulled over got some gas and snacks. I pulled up the directions on my pre and off we went.
So take it with a grain of salt.