That is very nice and complete! There have been numerous discussions about that theme on the Ubuntu artwork mailing list. The author has spent a lot of time and effort to make that theme as good as he possibly could. I joined the mailing list because originally Ubuntu was going to use that horrible circles wallpaper for Intrepid. I was testing Intrepid and joined in the protest for better artwork. There were hundreds of Launchpad posts and many of us got on the mailing list to have a voice and see what was being done.The results were pretty good, at least Intrepid's default wallpaper has some style. I test Ubuntu because it is what we use as a base and my stepfather runs it on one of his machines.
I see all kinds of awesome artwork that Ubuntu passes up on the mailing list.