Pros...
Themes are nice, offers preview, and impliments the changes across the mirc windows.
updater is a nice nice feature
Media player had some thought put into it.
Nicklist colorer is independent of theme, you can switch it around however you want.
Sound effects are kind of cool, and you can turn on or off each one, or the whole bunch.
I really like that floating lag meter, it's sweet.

Cons...
The Public/Private portions of the popups could become a problem, if you hit public and meant to hit private it might cause a problem. I'd put a spacer '-' between the two options.
Media Player doesn't offer a volume control.
Theme changer Unfortunatly it doesn't fix up the spoken text to match the theme.
Nick Completer is not customizable, you have to use portion:

Conclusion...
Not bad, mostly eye candy with some nice options controls. I think a theme designer and more customizable nick completion are needed.