Android devices and music making don't really go hand in hand, mostly due to a latency issue. Enter iRig UA: a zero latency, universal audio interface for Android 4.2 upwards.
The unit itself is at least twice the size of the HD-A and made entirely of plastic. While portable, once cables are plugged in, there isn't enough weight to stop the interface from wandering about.
The iRig UA comes coupled with AmpliTube UA for free, which only features a few effects and amps, with more available as paid content.
If you absolutely have to have zero latency guitar modelling on Android right now then iRig UA is for you, as there isn't another universal solution available. What we hope is that more products are developed on the Android platform, offering more choice for users. It's still early days though.