[One of the students] and 27 students in the Applications in Exercise Physiology class tested the impact of playing the Wii boxing game for 30 minutes against a 30-minute walk in a local park and an equal amount of time doing a boxercise video.
Every student did each activity and their heart rate was measured as well as how hard they thought they had worked out for all three activities.
They found that the Wii did get people off the couch and more active but, as a cardiovascular workout, it didn't pass the test.
They found that the walk in the park was the easiest (though they didn't say how fast they were walking), followed by Wii boxing, then the boxercise video.
I would argue that the walk in the park is a better exercise for the very unfit or overweight person, since it is a weight bearing exercise that uses the large muscles of the lower body. IANAD or PT of course. And Wii Boxing is the one Wii Sports game that gives a fairly decent workout.
(Comments have been closed on this post, since it seems to be a spam magnet. Mentioning "Wii" seems to do it.)