To be honest I don't like default Blender icons. I never did, bit since I'm not a coder - and not familiar with compiling at all - I couldn't do anything by myself.
Then the Day came â€“ Broken (Matt Ebb) wrote a patch that made possible changing icon set â€œon the flyâ€ without fiddling with source code. Finally common user â€“ just like me â€“ could take icon show on the road. I always wanted to get back to times when I had free time enough to make a small graphic designs just for pleasure so the patch seemed to be perfect opportunity to play a bit. Things in time turned out to be a bit more complicated and serious.
Current Blender's code structure (up to 2.4x branch) efficiently limits everyone's effort to clean up GUI inconsistencies just by redesigning graphical elements - that's one of goals of the big cleaning/reorganisation leading to Blender 2.5. None the less â€“ apart from under-the-hood stuff - good design could make messy GUI look more attractive, clear and friendly, so that was the point â€“ to make everyday using of Blender pleasurable.
There were several problems that one could solve just by playing with current icon set structure:
- inconsistency of graphic style all over the whole interface;
- unclear, ambiguous graphic design of specific icons;
- painful lack of visual codes.
All that has to be done was to focus on those purposes - sounds easy, but without community help and support it wouldn't be such a joy.
I'm far from being fully pleasured by final (actual) result, but it seems that community likes the new icon set and developers decided to make it official part of 2.5 branch, so there're chances that soon I'll need more feedback from all of Blender users.
The whole story (way too long) and icons' so far evolution is written down in the BlenderArtists.org forum's thread.