Arty photography made easy

The range of free or cheap apps available on tablets these makes arty photo manipulation ridiculously easy.  One effort by my primary school daughter, for a school project, for example:

I am still a little surprised, however, that it is hard to find a photo app that really does everything you can on (say) some PC software.  There is usually something I can't do on my Android tablet.  Then again, I haven't gone and just got the Adobe Photoshop Touch app, which I see is only $10.  

This will probably be my Christmas present to myself.

PS:  for anyone who cares what I think about apps, I find Sketchbook Pro is really a very good art app which is very useful for dealing with photos too.  It does take a bit of getting used to, though.