there are a couple bugfix's for 3.5.3 see
http://forum.bytesforall.com/showthread.php?t=8756 and
http://forum.bytesforall.com/showthread.php?t=7654
When ever a release comes out, if a bug is found, the fix will be put in the 'New Versions & Updating' forum.
As for when 3.5.4 will come out, it is waiting review by WordPress (and I wish they would hurry...sigh)