Games on the VC are exact replicas of their original forms, so if you've already played the game, you know exactly what you're getting. It will cost you the equivalent of $10 and will then appear on your wii menu as a channel.
Pokemon Snap is the first VC game that has an added feature. This feature allows you to post pictures you take in the game to your wii message board, which then allows you to preserve them, import them into the photo channel, as well as send them to friends you've exchanged friend codes with.
Feel free to ask more questions if you need. Have fun with your wii and happy forumming.