DS: Messier doesn't do much and there's not much to do. Think of it more like a virtual but sadly boring planetarium
There's not much to say about this game. While educational in a very basic sense, there isn't much of a game here. You stand before a night sky with the ability to scroll the stars above you though their "rotation" around the earth (clearly this isn't how it really works, but that is the effect from the earth's perspective). You then have the option of bringing up all of the constellations to view - which is nice and interesting. The game then, if you choose to accept it, is to clear the constellation lines and then re-mark them into the sky.
The problem is that A) this isn't very fun, though I do love planetariums and constellations. There isn't much to do here - the interaction is pretty boring and more of a really basic memory game. there's so much interesting about the sky. what if you could lock onto a star and read its stats? what if you could make your own constellations? what if you got a history lesson on the Phoenecians or Greeks? what if what if what it???
and B) the zoom/search mechanism doesn't work well. When you're zoomed all the way, when you move the joystick to search, the degree of movement is based on your zero-point body, not on the screen dimension. Therefore if you're zoomed all the way out and you try to adjust the screen you'll fly way off (as if you were zoomed all the way in and searching).
Bottom line: if you like stars buy a poster and skip the game.