I played the Wii version of this game (which is a fine game too) and expected the DS version to be watered down like the DS version of Ghostbusters (not recommended). I was wrong. This is almost a perfect port of the console game.
The game is divided up into 4 episodes. Like the original show there is a mystery which by the end of the episode you (hopefully) solve. The game play is well done. You feel like you are in a cartoon, the cut scenes are very good and feature voice acting from the characters in the recent Scooby doo dvd film.
My only complaint is Scooby is a little on the easy side. Of course you are probably reading this to decide to whether to buy the game for your children at Christmas and the difficulty is perfect for a child, the easy difficulty makes this a good game for an adult as it works well in a pick up play for a few minutes type of situation as well.
The bottom line is it's fun and worth your money. Your kids won't be disappointed if they find this under the tree and you may have some fun with it as well.
I hope developers will take note of how to do a DS port right and put the time and effort into future releases as is evident in this game.