It's very pretty, and very atmospheric, but after you've...I guess done it once there's not much reason to...er...run the program again. So I think it's very cool, and I think the art angle of it is pretty neat, but it's not a game by any definition of the word.
Now, whether it's worth $5 depends on the buyer. If you think about the price-to-time ratio of a game (the cost against the amount of time playing), it's a ripoff. If you compare it to a movie, even, you still lose out. But, I think the description in the store is about right: it's a painting you can walk around for $5.