The main difficulty was handling the hundreds of shapes as they overlap each other. This was made less troublesome by introducing layers for each major part of the painting (as shown below). I went for a painterly feel. It's easy painting smooth images in vectors, but this soon becomes boring to look at. This way, every time I look at the artwork, I have something new to see. The overlapping colour transparencies always yield a combination of beautiful colours.
The reference photo I used is shown above and below is the final painting. The portrait shows a textured background that was created in Adobe Photoshop using the cardboard cutout filter and converted to vector using CorelTRACE. All in all, I had a blast and believe the result is well worth the effort.