From the Soundcloud description:
___________________________________________________________________________________________________
This is a demo song with 14 instances of Heat Synthesizer (heatvst.com) used to create a whole track. Except some drum samples and FX, only Heat Synthesizer is used to create this song.
___________________________________________________________________________________________________

Do not why but I forget about Heat Synthesizer and always get surprised everytime 
I open it up how good it is and would say that it is one or maybe the most advanced synthesizers you can get for Android. It does not hurt that it sounds very good to!
Was playing with it some days ago and now with full midi control there will be a lot of playing with it over the weekend.
There is a list of Midi Controller Mappings on their website and it seems that it covers all 
or almost all the functions of the Synth.
Definitively worth getting if there is any interest in synthesizers.

Update:
___________________________________________________________________________________________________
● Added support to modify parameters by midi controllers. 
    A full CC list can be found on the web page
● Added "Reset" menu entry to reset all parameters to a default state
● Various UI improvements
● Various bug fixes related to VST integration
___________________________________________________________________________________________________

Play Store link:
Heat Synthesizer Pro BETA

To see the Midi Controller Mappings:
http://heatvst.com/wp/midi-controller-mapping/

Good, clear and to the point on how you can improve your low end if there is a usage of much bass frequencies in your music:
http://www.residentadvisor.net/feature.aspx?1211

G-Stomper Studio, VA-Beast and Rhythm updated since a week and for me the great thing is that it is now with X-Y pad for filters and effects. 
Was working on a track in G-Stomper when it came and now it would be hard to go back 
to how it was before. 
Would not think it was a big thing on paper but in practice it makes a huge difference. Making it easier to find the sweet spot and recording automation is a breeze, of course for live tweaking it is an obvious advantage. 
Strangely enough it is not too many apps that uses X-Y pads the first that comes to mind is the Mikrosonic's SPC Sketchpad and RD4 / RD3. 
Now I wish that SunVox and Caustic used X-Y pads to, for at least the filters!

The update:
_____________________________________________________________________________________________________

Simplification of the main Step Sequencer (main view)
All Piano Keyboards got note labels
New setting to change the overall fader + XY-Pad behavior to "relative"
New XY-Pads for Filters, EFX and Master EFX
Overall Graphics improvement (technical preparation for the upcoming re-design)
New Pattern menu on Efx, Master and Timing & Measure
Full release notes at http://www.planet-h.com/g-stomper-studio/gst-whats-new/
____________________________________________________________________________________________________
Play Store link:
G-Stomper Studio 
G-Stomper VA-Beast
G-Stomper Rhythm

Getting one video explaining all the concepts instead of the other tutorials that they have released may make things easier for many. If it still seems a little bit confusing it is not too hard if you download the application and play with it for a while watching the video. It is for free and totally functional and if there is a attraction to the app you can pay some money and get a higher audio quality export option enabled. 
There is also a new update and one thing that is not so common is that they have made it possible to connect directly with their new forum directly from the application.
Another thing that is interesting is that if you sign up now for the community ( where you can download and share samples ) you get a thousand coins to spend on buying samples.
The samples do not cost much at all per sample. ( If I remember correctly it is about ten coins per sample which translates in real money to about a cent for each as you buy 1000 coins for about a euro/dollar. ) There is also around a thousand samples / loops for free.
In either case as said before it is easy to try everything out for free.

The update:
___________________________________________________________________________________________________
Version 1.07 contains a lot of improvements and fixes, the biggest ones are:
- Now we have a public forum(!) in the App for the Community, so you can get help from others quickly, view the News, Tips and Tricks, and post your own entries.
- Immersive Mode for Android 4.4 available now. You can switch it off in the settings
- You can now assign live recorded sounds to your projects and instruments, and play them in the lists
___________________________________________________________________________________________________
Play Store link:
uFXloops

This is a nice article / post from one of the oldest ( or the oldest ) websites still going strong regarding mobile music making and how he sees Android and its musical possibilities. 
One interesting thing is that he does not compare it with iOS but talks about Android on its own terms.
To read it go here:
http://www.palmsounds.net/2014/07/where-we-are-with-android-and-where-next.html

and extra props for recommending Musical Android!!!

If not using Audio Evolution Mobile with a USB Soundcard it is now a much improved latency correction built in as shown in this video.

Play Store link:
Audio Evolution Mobile

Almost all or all of Mr Nightradio's SunVox compositions only contains the internal synthesizer engines and no samples and it sounds that this is the case here as well.

There is sooooo much sample material to take from this video clips that are mostly from the late eighties. So if you need an endless supply of vocal phrases...

There is only two horror movies the last years or so that to me was interesting and this is one of them. 
Maybe not really so much of a horror movie as a metaphysical meditation presented in such a way that it can lead to some serious nightmares.

This album was made fully in SunVox on a Android tablet and just the 
final mastering made with Izotope's Ozone. 
Do like it a lot and did a interview with Jimsey that you can read here:
http://www.musicalandroid.com/interviews/jimsey-interview-with-a-great-sunvox-artist

The developer of Moon Synth and Psycho Flute ( both recommendable ) was recommending this and it was a good thing as even it is limited soundwise it sounds very good.
Actually it just contains three sounds but I am already in love with one of the sounds 
( an olden time electronic choir sound ) and see me using this as an instrument just for 
that sound.
It functions as most of the other Theremin apps and has the possibilities to adjust Octave, Scale, Key, Size and choose one of the three sounds. It is possible that many would not really like any of the sounds but for me like said am in love with one of them and being multi touch and with the possibility to directly affect velocity it can become a good thing to add to your arsenal of instruments.
Plus it is for free and no publicity!
EtherSurface

Ha ha this must be the first time there is a posting with a real crap app!
Have used this in some music as I like the cheesy but beautiful sound and want to start to mention some of the virtual instruments as well.
This is basically a app that have sampled some electronic choir and packed it in with a keyboard. Full of publicity to! 
That said it is a specific sound that for me is useful and will use it more than once.

Play Store link:
Best Piano Choir