I'm not sure what you want to accomplish, but unless it's a retro thing, Haiku is IMHO on par with BeOS and runs on new hardware.
I don't have GPU accelerated 3D working, but it's of little use to me ATM.
A few default preferences that drove me nuts that you may want to change:
- Keymap shortcut setting for Ctrl instead of Alt key on shortcuts. (ctrl-C, etc) Haiku defaults to Alt, but I like Windows/Linux mode.
- The mouse setting so that the first click both focuses and sends button events. (Otherwise you click on a background window close button and it only focuses the window)
- Tracker preferences for Show folder location, Single window navigation and show navigator.
After those it's pretty nice.
It's still a love it or hate it look though and the other themes aren't complete.