In this site’s about section we discuss why to use a reverse macro lens, so I thought it would be important to get some comparison shots with real macro lens at a close to the same magnification.
Here is a sample of the difference on a Canon Xt shooting a Canon 100mm Macro vs a Reversed [...]

User MawcDrums on youtube uploaded a quick how to video about how to open/close the aperture when you are taking photos when you reverse a camera lens for macro photography.

The results are a bit iffy to see on the screen, but you get the idea.
It was taken on a Canon Xsi with the kit lens.