I drew the robot thing that I'm using as my new blog image last night in Acrylic. It's still a pretty cool product... just not one that I have a lot of use for. I can't draw much of anything. I can draw and shade geometric shapes, and that's pretty much it. It still may be worthwhile trying Acrylic out for some what I currently use CorelDraw for; vector-based icons and small pictures. But, it's certainly nothing to make me put away CorelDraw or Photoshop.
It would help a lot of what you were drawing rendered as you draw it. Currently, everything you draw exists as a grey texture until you lift the pen, which is fine for simple strokes, but makes it hard to know what you're actually doing when you're trying to shade an area in.