A new update is now available. Please take special note of the warnings this time:
WARNING: As of this build, the new rendering system is enabled by default. The primary focus at this point is compatibility, not performance. Compared to the old -ddraw system, it will appear slower when fully unthrottled because there is not a good mechanism to skip the render if the graphics hardware is still busy like we used to do. If you have any trouble getting a correct display or if you get warning messages printed out when starting MAME, please post about them on http://mametesters.org.
SECONDARY WARNING: The command line and INI parsing code was rewritten. If you notice any problems with handling of parameters in either case, please report the bugs on http://mametesters.org.