This game here, for the price its going is more than worth it. Just to be able to walk around and look at the art style is enough for me It's absolutely beautiful. I'd love to see some clones of this art style work its way into other genres, because im really enjoying looking at it.
As far as the gameplay itself, i have to admit it does leave a bit to be desired. Theres nothing really wrong with it so far from what ive seen, but there isnt anything groundbreaking either. It is a simple shoot em up, with simple controls. Although i see there is a lot of upgrading that can be done to your ship so that may change later on in the game, there may just be tools to come that make the gameplay more complex.
My opinion is, if you're even the slightest bit interested, go ahead and grab it now while its on sale. Hell, grab it while its not on sale. $4? Extremely nice game for that price. AND it drops trading cards, so you could get a bit of that 3-4 dollars back if you wish