Nice Work! Rated 4 out of 5 stars
For this being your first theme you've done an awesome job. I really appreciate the fact that the nav buttons have an obvious visual effect on mouse overs. A lot of theme developers don't pay much attention to that when they developer their themes but I think that is an essential feature that should be incorporated into all themes.
I can certainly appreciate the time and effort that you put into your this. Far to many people don't know how much work it is to write a theme. All that they have to is open a .jar theme file and look around.
I look forward to future releases that I hope will include skinning of more areas of Firefox's interface.