Lindsay Benkel of the Freaking Awesome Network wrote a really nice review of Guppy:
Lindsay wrote: The visual style of Guppy will grab you immediately. Reminiscent of Japanese block prints, the thin outlines filled by globs of wispy watercolor layered over a stark, white background convey a sense of ease that will draw you in for at least five minutes of swimming relaxation.
In a world that often seems dominated by games that require at least a 100 hour investment, I was pleased to find that something so quick and simple could still be executed in such an elegant and truly enjoyable way. Christiaan Moleman has done a wonderful job of creating an experience that calms the brain and genuinely makes you feel a little better (that’s the power of charming little fish). Guppy can be enjoyed by both young and old and can be picked up, or put down quickly making it essential for any PC desktop. You better believe that next time I get frustrated with computer work; my breaks will consist of swimming around to discover new parts of the pond till its calming effect helps me get back on track.
The game may not be technically finished yet, but it's great to get a response like this. :)