I'm often interested in trying this type of applications. There are quite a few things I did not like:
1. Demo is limited and nagging pop-ups are too frequent.
2. Price is expensive at $39, or $30 if I act now to save 25%. Reminded me of one of those cheesy TV infomercials.
3. Size seems a bit excessive at 25.2 MB.
4. It is a bit slow.
My favorite application for finding duplicates is Find Duplicate Files. I always go back to it. Here's a brief comparison with Tidy Up! I created a Folder with 91 items, 190 MB total. I included a wide variety of files (e.g., URLs, Word, Excel, PowerPoint, MP3, Images, Text, PDF, etc.).
I duplicated 15 items. I changed their names and/or extension. I tried the Basic Mode originally, but I could not select multiple criteria so I switched to Advanced Mode.
Time: TU! 9 seconds, no items found. FDF About 2 seconds, 15 items found.
The "best" result I got with Advanced Mode was when I only selected "Total item's size is same":
TU! 10 seconds, 16 items found. TU! mistakenly identified one file as being a duplicate. The files are indeed different, so this is bad. As mentioned, I had only 15 duplicates.
Although the list showed 16 duplicates, the top of the window displayed "Duplicate items 9"
Including "Contents of Files Options" for this search:
TU! 8 seconds, 6 items found.
Although the list showed 6 duplicates, the top of the window displayed "Duplicate items 11"
This was just a quick test, and when I use Find Duplicate Files I typically check multiple folders and hundreds of GBs of data. Speed and accuracy are VERY important.
A second quick test using a 6.7 GB mostly with MP3 files.
TU! 0 found using "All kinds" in Basic Mode
TU! 0 found using "MP3 files" in Basic Mode
TU! 1 found using "Item Size" in Advanced Mode. This was a text file.
FDF found the text file AND a duplicate MP3 file
TU1 checked 129 items in that folder, while FDF scanned 764 files. In spite of this, once again FDF was much faster than TU!
If I had no other frame of reference I would think that TU! worked great. After all, it did find many duplicates. Unfortunately it also left out many other duplicates or identified files that were different as being identical.
One thing I did like about TU! is the nice Preview that allows for a quick comparison in case of doubt. Particularly for audio and MIDI files the preview is better than that of FDF. For other files FDF does a great job, in some cases better than TU!