Well, I was recently testing out some app's on vista and unfortunately I have to tell the truth about this program. And this is the programming side of me talking.
Although it is a great tool for hard to find options in Vista I have to say that there is not much to it. It is nothing more than certain tweaks that might be hard to do if you are not familiar with Vista. Now, I don't have DWM support so I don't know what that looks like. But the Misc. Tweaks could be a lot better.
From my perspective as a programmer, it needs to be fully updateable on runtime. So when I change the size of the icon, I don't need to restart explorer. This may shy folks away. Now, with that said, I have noticed that some people were asking about XP as well. Here is my suggestion.
Make the program like TweakUI. Then add features that are only available in Vista. This way it can be used on XP (For tweaking purposes and advertisement) as well as Vista. Some things that are definitely a must for this program is possible just keeping the visual styles alone. Red Backgrounds for toolstrips with black text is very hard to read. I think that it does need to have something that stands out, but instead of just tweaking colors take a look into <a href="http://www.sunisoft.com/irisskin/" target-"_blank">Iris Skins</a>. Very nice customizeable skins.
Now, for someone who is not familiar with Vista or any other OS I would say 10. But it is hard for me to even give it a rating right now because I don't know what to think. Sorry.
Also, corey since you are using VB.Net 05 I would look into using API commands if you are not doing so already. VB.Net Framework, although nice, holds back what you can really do.