Regarding the muffled audio on Sound Blaster systems it is Windows that is resetting the SBX Pro Studio settings to enable Surround and the Crystalizer (Creative's spelling). Disabling these settings will return audio to normal.
Game capture cards will probably need to be reset as well, and of course any SLI system will have SLI disabled. This is probably going to be 'normal' behavior with Windows updates from now on.
Also, make sure that your system clock is set to the proper time before update. There have been a few people that had to reactivate (or were told to), but this simple fix prevents the problem.
If you use a TPM module with your motherboard and have run into an update issue over the last two days, this has been fixed now and your system should be auto-authenticated and updated without a problem. This was causing an issue on my system, but as of this morning the updates were not only faster, but involved fewer reboots.
Another change is the way that default programs are maintained. Yesterday it was a lot more clumsy, but today it is just a double click on your program of choice. Nice!
EDIT: Make sure that Firefox (if you use it) is updated before you begin the update. You will have to reinstall CPU-Z and GPU-Z if you are using them (as usual). There are a few other benchmarks that may be affected as well.