I remember building my first pedal board out of an old record player. The size was wide enough that I could hinge onto my Peavey Rage amplifier. I had a Wah/Volume, Reverb and Doubler pedals which I affixed to the board and plugged into the power strip. It was crude, but it worked really well.

Today, all you need is a smartphone to not only get all those pedals, but a plethora of amps and microphones as well. Digital guitar modeling has majorly progressed in the last 5 years - especially with companies like IK Multimedia who are pushing the boundaries for musicians. A guitar player might just walk in with their ax and a tablet that plugs right into the soundboard. No more amps. No more pedal boards that lie on the ground to get beer spilled on them.

The iRig has been pushing the limits for guitar players and creating the sounds they like their Lucy to make. For the last couple years though, you could only use it on an iPhone or iPad. But that all changed this year when they came out with the iRig UA for Android.
About the iRig UA for Android Devices

Slightly different than the iOS counterpart, the grey UA has the headphone jack on the box. An aux insert is also available for bringing in backing tracks to practice with. The device uses a special USB micro to USB micro cable so the device can plug into your Android device. Call up the Amplitube software and start playing with some powerful sounds.

Change up your pedals in pre or post amp to get the right sounds your looking for. The free version offers 4 different pedals and 3 different amps to choose from. In-app purchases give you more modeling options, from brand name amps like Fender, Orange and Ampex, to a great mix of distortion, delay, EQ, Wah, and compression pedals.

The UA is a 32-bit digital signal processor with 24- bit conversion with no latency. UA will also work on your PC or Mac computers to use with programs like T-RackS Classic.
Get the iRig UA - Get the iRig HD - Get Amplitube App for iOS

Compared to the iRig HD for iOS Devices
The advantage does go to iOS for functionality, as there are more pedal options, and the software comes with 3rd party in-app upgrades (like the popular Loopy app), drum backing tracks and a multi-track mixer.

However, when it comes to the modeling sound, both iOS and Android (in this case, a Nexus 5) push out some great sounds. iRig HD uses the iOS headphone jack for not only listening, but attaching other iRig devices, such as the Stomp pedal.
Disadvantages of iRig UA
The device does not come with a power pass-though option. Therefore, your phone battery might not get through a whole gig - depending on what you have installed and the type of battery inside your phone. Speaking of which - not all Android phones will work with the UA. Your phone must have 4.2 installed and can host USB OTG.

A belt clip option would have been nice for the device so I could attach to a stand or on my guitar strap. This goes for the iRig HD as well.

Finally, I can't save models to send to other devices. I had to manually set up the Android and iOS boards to match for the tests. If I switch between devices, I can't take the in-app purchased options with me.
iRig for Android or iRig for iOS?
For this, you'll have to watch the video where I work on some sample licks and compare. I used the Nexus 5 and iPhone 6 for my tests. An iPad or Samsung Galaxy Tab might be good tablets if you want more real estate to work with.