I hadn't updated/used SC since OS 9 so was very curious to see what had changed for X. I've tried only three features so far - empty folders, internet-related files, and orphaned prefs.

-Empty folders: it finds them, but you need to set exceptions to avoid messing up the folder hierarchies created by many apps.

- Internet-related files: most of those found could be easily cleared by a reset or purge from within the app itself. It also located a collection of archived web pages in my user data - you need to set items like this as exceptions, to avoid an overly exhuberant delete of important data.

- Orphan prefs: this was one of the most useful features for me of the old OS 9 version, but seems less useful now. There is the problem noted by other users, of the the inconsistent way some developers identify their prefs/plist files under OS X.

But worse, SC also flagged a number of active prefs files from current versions of applications. Again, setting these as exceptions will work around it, but the user definitely needs to be careful when going through the list of results.

Conclusion: many features and merits , but does require careful setting up (and reading lists of found items) to avoid doing more harm than good.