This and Black/White are the standards Pokemon games should be held to. The story's engaging without being too in-your-face, the Sinnoh region is the best designed region in the whole franchise, a lot of my favorite Pokemon are from this game, and it's super easy to just pick up and play.
The only reason this is 4.5 instead of 5 is because of technical issues slowing down the game in-battle and while saving.