This looks to be a pretty new release from YanicSoft
(Released on Dec. 28, 2004) so there's not a lot of information on the reviews of the software.
It does say that there's a way to create a backup before making any changes inside Advanced System Cleaner. I would suggest that you definately do that. After making the backup, run the application and if there are any bad effects to your computer, you can always restore the registry.