Shortest "killer feature" is probably the re-use of native vim buffers inside of telescope. So one cool thing is when it does a preview, it will show you the literal buffer (so it will have exactly the same colors, syntax highlighting, etc.) wherever possible.

Longer answer is I think it's quite cool to be able to not have to serialize/deserialize everything within telescope, so you can pass around objects (a.k.a. lua tables) that have function references, etc. that allow for very fun extension of the general API.

Another part I guess is that every part (that I have been able to think of thus far) is customizable. So you can change (per-search) the sorting algorithm, the display, the highlighting, the preview, the search text, etc. So you can fine-tune each aspect of it for the particular search or just your general preferences.

Also, I made it just because I was having lots of fun with it. I think fzf is a super awesome application (and plugin), so if it's working well for you I don't think I would switch!