I am testing the 30-day trial version (downloaded here) and was put off by the windows-like feel at the beginning. After a few minutes though, you really appreciate the simple way the program works. (And though it may be windows inspired it's at least not ugly, if that matters)

If you have large chunks of data and need to compare folders and even MOVE or sync folders, I have found this to do the job reliably and quickly (scanning 1200 files / 100 GB in a few seconds). Folders / Files that are identical are greyed out in the scan result list, different files / folders are bold. A double click reveals their differences (ie in text files).

I shall report back and update this review if I run into serious problems, but at the moment, I look forward to weeding through a few hundred GB of data before archiving it with this software.