I went ahead and install 0.24 on both my Mac and Linux systems (I have a Linux backend, and a Atom/Ion Linux frontend I use in parallel with my Mac Mini).
The Mac version of the frontend is still a bit sketchy for me. 1080i video looks quite good, but I continue to have problems with 720p channels. The video drops frames all over the place, so the video looks very choppy -- especially with sports content. If anything, 0.24 made the 720p problems worse.
On my Linux frontend, which is an Atom processor on an Nvidia Ion platform supporting VDPAU acceleration, 0.24 seems to work quite well. While it might be a bit less responsive than 0.23, the video performance is slightly better.
It looks like I'll continue to switch over to my Linux box for much of my MythTV viewing, and use the Mac for everything else.
I'm hoping the ongoing XBMC / Plex projects to integrate MythTV DVR backend support with their frontend will pan out eventually.