Hi there!
To be honest, one of my first feelings was: Ouch! Why green vs yellow?
So you can count me in the
I-want-theme-selector crowd!
Besides, SMF admin panel let you know how many members uses a particular theme, and this is a valuable info IMO.
The previous theme was, among all SMF I have visited, a true "coup de coeur" because It used a combination of colors, saturation, visuals and readability that I found really blowing and unusual, even in 2010. Now I'm not strongly opposed to this new theme, but I'm not really fond of, mainly because of the palette and some of the minimalistic icons. The C0BC90 + A9B293 combo placed here and then hurts me, for instance. Also the topic icons seem not understandable-at-first-glance enough to me. I won't name some sections in particulars because this is a general feeling I have.
Now, since I'm also currently in the middle of CSS-ing a SMF forum I know that it's a difficult task, and that kicking the habits don't please everyone, especially when "everyone" means 4.000 members

Anyway, Good luck with this new theme!