Good, if you're a hard-core Harvest Moon fan. The controls take a while to get get used to. Not the worst, not the best.
You must be extremely careful when holding stuff in the game, like fodder and crops. One wrong touch on the DS screen could cause you to drop and waste away all you're hard work.
Controls is one of the main flaws, but don't let that stop you from buying the game. I got used to the controls after I played for a couple hours (Yes, hours. I'm used to playing other Harvest Moon games). But overall I enjoy playing it. I think the graphics are pretty good for a DS game (Much better the Rune Factory), and of course who doesn't love the annoying music that changes every season. This game also has a brand new storyline unlike any other Harvest Moon game. You get shipwrecked, and must use your farming skills to make the deserted island prosper.
So, as I said, if you're a die-hard fan for Harvest Moon, go for it.