I've installed this, and you can see a working demo of the non-GD verification
here.
The only problem I found is if you fill the GD-verification out correctly, but have forgot to fill in one of the other required fields (such as password), then when you refresh and go back, the image-verification is sorta screwed up (as in the images wont show). This may only be for the non-GD version though, since I don't have GD installed, but am planning to.
Good job once again Slynderdale