Just a heads up, as I'll bet a lot of people who post here own the game and haven't played the demo in a long time ... but the demo says the game costs $30, but on the website it's $20.
It's not a HUGE deal, but in terms of selling a really fantastic, under-appreciated game, people seeing a $20 price tag vs. $30 for an indie game is a massive difference. $30, for many people, is utterly unthinkable, no matter how good a game is... but $20 is starting to get into the reasonable territory. ($15 or $10 of course being "wow, got to buy this" for a game this good.)
That $10 gap could also be the difference between someone doing the right thing and supporting a really top-notch indie developer ... and then just pirating it. (Though even if they do the latter, hopefully they'd have enough sense to eventually buy it if they find they get a lot of enjoyment out of it.)
Also: anyone else find that the gamepad works a lot better than the mouse? I found that the mouse controls are pretty well-done, but, for example, already the first boss battle became kind of frustrating with lack of mouse precision until I plugged in my gamepad, after which it was a lot more playable. I love Aquaria's freedom of movement, and haven't felt this interested in exploring since Super Metroid (to which I see a few somewhat obvious in-game references). The mouse enhanced that somewhat, but the gamepad lets me be far more precise.