I get a obsessed with process and programs and I recently (after a year of the subscription) tried the demo for ArtRage included with Imagine FX magazine's dvd supplement. It's actually a really intuitive and user friendly program, though at first glance it appears quite complicated. The fact of the matter is that ArtRage is more complex than Sketchbook Pro, but satisfyingly so. And simpler to use than Painter and unlike Photoshop (and more like SBPro and Painter) it feels more like a drawing program.
Right off the bat you can choose different types of canvas and papers to draw on. Each with a pretty good representation of the tooth and grain of the real thing. When your canvas is set you have the option of including a "tracing layer." This is one of my favorite features as I do a lot of digital lightboxing. The tracing layer, upon commitmnet of the new file, sets up a base layer of the image you choose at 40% opacity with a drawing layer above it. You are ready to go in no time!
Now that you are in your file you can snap on the Refs tab to start pinning up imagery for reference and color picking. This is my next favorite feature in ArtRage since I almost always have inspriational images up when drawing. Unlike photoshop, where you have to open new files causing a cluttered workspace or transfer them to and transform them on your new work file, ArtRage tacks them directly to the file's canvas already minimized. At the tap of your pen you can zoom in/out and move the Ref file around in it's own confined photograph frame. Very vifty indeed.
The rest of the UI takes a cue from Sketchbook Pro with the radial menu for brushes and colors, each with their own clickable settings tabs. I do take issue with the lack of canvas panning & zooming tool readily available, though it does have a nice multi-tool for this in a pop-up. Maybe after more exploration I could discover a way to make it a constant menu on the screen. Also, it's hard to beat Sketchbook Pro's floating brush sizer. While ArtRage has a similar tool, it's anchored at the bottom corners and has less margin for sizing.
I think this is a very versatile program for any artist and I would encourage anyone to try the free demo. The demo, however only lets you save files out as ArtRage only types.