I have found Jon for me that taking a picture flattens the textures and colours and like you it is the spontaneity of drawing I like which gives me pleasure. I tried Inkpad which was OK but I prefer Sketchbook Pro and Adobe Ideas, maybe Paper by 53 as well, these are the ones installed on my iPad. I still don't like using my finger as a drawing tool give me a pencil shaped thing and I am happy. Frances SketchBook Pro and Express are available for the Android tablet, the Pro ver. cost in UK £3.41 and the Express ver. is free. You get a 30 day trial for free and just over $6 can. seems not a large price to pay for a paint/vector programme.