During installation clicking on Other in the partition mounting menu crashes the installer.
Also I got a kernel panic on the first boot(right after the udev warnings). It's the same one I've been getting a lot in RC2 - http://imageshack.us/photo/my-images/194/kernelpanic.jpg
However, that was the only time I got it on RC2.1 so far.
Also I didn't get any lockups so far.
Time will show
On an unrelated note:
Currently ffmpeg version included in RC2.1 is 0.6. A little while ago I've build ffpmpeg-0.8.2, which has a lot more functionality than the old one(in testing), and a few deps(got lost on the way). The problem with installing it from the repo is that it breaks all video players(and maybe other programs too), meaning they have to be rebuild against the new ffmpeg.
Could the new ffmpeg be included in the next iso, this way there won't be any confusion over which players were build against which version. I've already build a new vlc version against this new ffmpeg and it works great.
There's a bit of effort tied to it, since the players have to be rebuild(I coundn't find any recent SlackBuilds for mplayer and xine, otherwise I would've given it a shot), and testing to see exactly which apps were broken.