I played through the first of apparently 4 or 5 worlds just now, and this game is beautiful.  While so far the puzzles have been more action-puzzle oriented than pure puzzle, requiring you to stay quick on your feet as much as think ahead, the game is absolutely stunning simply for the sheer amount of effort that 2D Boy very evidently put into every aspect of the game.

As I type this, the lines of text on the screen on bobbing peacefully up and down as if they are lines of goo.  Gragh.

I think I enjoy the experience of World of Goo for the same reason that I enjoyed the experience of Spore, which is, in fact, just that.  Let me disentangle that: I enjoyed the experience because it's enjoyable, in both cases.  I think a shared element is a certain sense of wonderment.  In Spore, it came from the feeling of scale in the game: there are things bigger than you, smaller than you, and right there struggling along with you, and for once it doesn't feel like the game world cares if you live or not -- the game truly isn't about you.  In World of Goo, the wonderment that you feel as you play comes from an entirely different sorts, which is a very simple and visceral joy that the game manages to deliver despite its starkly simple -- and if you think about it, rather inane -- premise.

• Why is there no options menu?  I have a 1680x1050 display; I'd like to use it, thanks.
• Couldn't seem to connect to the internet the first couple of times.  Third time was the charm though.
• It's a neat feature that free goos flock toward your cursor, but highlighting precedence should go towards balls on the structure so that if I want to get at them I don't have to clear the way first.