Just to get it out of the way, I think it's safe to say that Flower is one of the best games available on PSN and one of the best, most unique experiences you can have on really any console.
(In Flower you control the wind using motion control, guiding petals of flowers through a landscape through grassy landscapes and blooming other flowers along the way.)
Right off the bat, Flower's presentation is simple and elegant. With very little to no text ever on screen, the game provides subtle nudges as to what needs to be done. It feels like some sort of natural instinct is sparked in the players mind. You're never told what to do... you just kind of know.
Now, that may seem cheesy sounding, but let me tell you: I'm not really the artsy-fartsy type. Flower, however, is THE most relaxing, soothing game you could possibly play. I honestly felt... well, good after playing for a few minutes. It's oddly very engrossing, and I found myself sucked into this world. That doesn't mean there's no "game" here. While no actual challenge is ever present, the game never feels unsatisfying. There is a sense of accomplishment as these landscapes become replenished and the trophies will certainly give hardcore players something else to do.
Note to graphics whores: this game is gorgeous from both an artistic and especially technical stand point. The number of individual blades of grass rendered on screen is stunning, with each and every one swaying with or against the wind based on your actions. The colors are also especially vibrant with a nice touch of motion blur adding to the general effect. Some could gripe about bland textures, but frankly that really doesn't matter in a game like this. You are doing your HDTV and PS3 a disservice by not owning Flower.
The music is rich, too, with some very plesant compositions and effects. The game also adds another level of interactivity with notes and chords playing as each flower is bloomed. The ambiance and wind sounds further compliment the presentation.
As far complaints go, Flower is indeed very short and can be "completed" in 2 to 3 hours. But really after finishing the credits, the first thing I wanted to do was play it again, not to mention the suprisingly tricky, thoughtful trophies (one playthrough yielded only 3 trophies for me). I think that's always a testiment to how good a game is: the desire to play again. Other than that I honestly cannot think of any way the game could possibly be improved. It looks fantastic, sounds just as good, and the six axis controls are sublime.
Flower is indeed worth your time and your money.
Special Note: I hear some people whining that there's no demo... Just buy it. Watch the trailers for the game. If the concept is even MILDLY intriguing to you, spend your money. Besides, I don't really think a demo would work well with game like this.