So far, my Sharkk works perfectly... of course, I've only had it for one day.
The Sharkk has 5 ports, 3 of which are designated for Apple devices (2 iPad and 1 iPhone), an "Android" port, and a "Galaxy Tab" port.
The iPad ports both put out 2 amps. The iPhone port puts out 1 amp. The Android and Galaxy port put out 1 amp each, but they use different voltages than the Apple standard.
I tested my charger with all 5 ports filled: 2 iPads, an iPod touch (in the iPhone port), a Galaxy S4 in the Galaxy Tab port, and a Droid 3 in the Android port. All of the devices charged simultaneously, and all had a full battery in the morning.
Honestly, for less than $20, I have not seen a better charging solution anywhere.