Sadly this is perhaps a measure of how desperate us GIMP users are. I'm just happy that GIMP is all going to be in one window. Its amazing that they finally decided to leave the old standard interface.
But relief and anticipation aside I have to agree with you that as far as aesthetics and design it is rather mediocre.
At the very least it is a start. Now that the maintainers are allowing the single-window mode to be created the onward march of open-source progress will keep improving it. It may not approach the elegance that Apple's designers deliver but we can sure as hell beat Adobe.
Edit: Did all of my downvote arrows disappear? I don't want to downvote anyone in particular here but that seems odd.
But relief and anticipation aside I have to agree with you that as far as aesthetics and design it is rather mediocre.