First of all I'd like to say I'm amazed by Art Rage. It's the best art software I've used. It perfectly combines a gentle learning curve with great basic features..and the more techniques and tricks I learn, the more powerful it turns out to be. Best art program ever.
With 2.5 version it only gets better. Using the previous versions I wanted an option to name my layers, because I get lost in the stack? In 2.5 that was added. Same thing for layer groups and rulers..
It's not perfect though
I use a huge tablet that has to be shoved out of the way whenever I want to type, so assigning names to layers is a minor pain. I'd love to see an option to write in a name or symbol to identify the layer. This could replace the layer thumbnail, since that's too small to see much when I'm just penciling in details anyway. Alias Sketchbook did this, from what I recall - I haven't used that thing in years.
Another would be 'merge visible layers.' I draw only on transparent cal layers and leave the white opaque canvas blank. Grouping layers and merging all in the group is one way to manage...another is deleting the blank canvas and re-adding it. But those are kind of cumbersome.
These are just trifling details though that would make an amazing program into a perfect one. I can't praise Art Rage enough.