Not sure why there is so much grumpy bashing going on here? I have been a Leap/Deep user for some years now. I have seen Leap go through some iterations and I have to say that; 1) it is very stable and, 2) the developer is very responsive.
I would not say that Leap is exceptionally fast at finding anything on my disks. That is, until I tag the items. Leap shines in the way it allows me to save searches as bookmarks and folders, and it allows me to keep those folders in order so that I can set up my own searches - and remember them.
I also use HoudahSpot which is my goto tool for finding anything, anywhere. You can save HoudahSpot searches as templates too, but it is much better to do this using Leap. HoudahSpot creates a new tab each time a new search happens, you cannot escape this. Leap shows any search you have, one at a time. To my brain this makes much better sense.
I do not mean to suggest that Leap only uses tags, it also searches by date, does spotlight searches, etc. I find that when I have Leap search it can take a while, especially if it has to go to the deepest levels in search of a file - even if the file is in the next folder over. Because of this I have found Leap to be extremely useful for finding AND ORGANIZING files - intended emphasis on the organizing part.