Great idea - bad product. Bought about 2 years ago, but only used it a few times for 2 reasons. First, the micro USB port felt very unstable and I felt I had to handle it very gently. It ended up falling out on me when I tried to plug it in around the 6th time I used it. Warranty was long expired by then.
Second, the surface is dark with clear dots, but when placed under your canvas, they don't seem to illuminate the canvas as much as I'm sure it was intended.