Sublime. Flower is the most engaging experience of movement, speed, atmosphere and space I've had in any game. The runner up, Eve Online, is not even close but even Eve is light years ahead of most games. Flower has room for improvements, nothing is perfect. But it might be the most innovative game I've played since Dune 2. It is not a classic game in almost any way, it is more an interactive experience of engaging fun rather then a computer- console- arcade- game. And it's better for it. It breaks most of the molds that hold this medium from growing but is never artsy or pretentious.
The only complaint I have with flower is that I have to play it with the SixAxis controller. Don't get me wrong, the 360 controller would certainly not be better and I doubt even the wiimote would be an improvement. A clunky piece of plastic simply doesn't do the experience justice. For preference I would have liked to play it using an iPod nano. But we can't have everything can we?
Flower. It's the best game in it's range (a short, small, cheap but luxurious experience). Buy it. You'll not regret it, I wish I was home playing it right now.
Thatgamecompany has really hit the mark with this one, let's hope they keep reshaping our perception of games and entertainment!