A friend has the wireless mic and he raves about it everytime I play with him. I don't know anything about the vision pack though. I did hear that on some games you could add your face to the game using the XBOX camera. So if you had to choose between a camera or a wireless mic, maybe the camera would be better.
The camera package includes a regular mic, Uno, totemball, and the camera. I believe it retails around $40's. Rainbow Six Vegas has a really cool face mapping system allowing you to put your face on the charector (sp).