The UI is very nice. However, DO NOT buy this app! Kaleidoscope v2.1.1 is crashing A LOT! I have contacted the developers twice in the past 6 months and they just shrug it off with nonsense replies that "...we are looking into it". Are they "looking" for over 6 months!? The problem is really simple. If you have two drives (say USB) and you want to compare the content of folders on one drive with the contents of another drive (using same folder structure), the first comparison passes, but after that, with each comparison the app will become increasingly unstable and eventually crashes. Who knows, it might even corrupt your drive(s) eventually. Does not worth 70 bucks for an abandoned app!!!