Good idea, and look well-executed.

I would add more images and examples of the application in use.

Also, choose more relevant examples... the only one I see is a comparison between the same image with color changes. Show something like a whole website project from early stage (sketched mockups) to later stages (details in coloring and font choices, or whatever).

Also, IMHO, the copy should focus more on the benefits for the designer (get better feedback faster, more often) than on the benefits for the client ("Save your clients the hassle of resizing browser windows, or printing...")

This is a great looking app and site, especially if you were learning as you went.

Good luck! Adriano