You'll either love it or hate it, but FlOw is ultimately an enjoyable game that's well worth the price.
What it is, however, is an entertaining, relaxing adventure into the depths of a synthesized ocean, in which you'll hunt other creatures for your own survival. The graphics and artistic design are spectacular (far greater than the Flash version), and the sound really involves you in the gameplay. Surprisingly enough, FlOw uses the Sixaxis controls perfectly, and it is very intuitive. It may seem awkward at first, but soon you'll be zipping around chewing up every kind of deep sea creature with ease.
Finally, comparing this game to Spore is confounding. This game in no way tries to compare to as ambitious a game as Spore. Likewise, I believe FlOw for PS3 differentiates itself from its Flash brother in multiple ways, including graphics, sound, and control.
If you're even mildly interested in the concept of FlOw, for only $7.99 I don't think you have much to loose. Enjoy the swim.