This is a pretty accurate assessment of many of the UI hacks available, though some are more uniform/usable than others. I tend to do most of my modification through system tweaks, dock replacement (2D here), icons, wallpapers, window management applications, and other such changes, rather than so drastically altering interface elements as some of the hacks do.
I'd recommend Iconpaper as a well-maintained repository for various UI modifications elements. They also have themes like MacThemes.
Though I haven't tried it, you might also look into Raskin. It's supposedly an alternative Mac interface (looks like a shell of sorts) with a different approach, although I'm not sure it's exactly the pre-OS X goodness you're seeking.