Updated: August 12, 2020
Application launchers are an interesting phenomenon. They are both an amazing piece of software and also something that most people won't ever really need - or understand. They sit in the twilight zone between the Internet and your system menu. Which is what makes them so difficult to design and implement correctly.
The best example of a successful tool of this nature is Krunner. It's integrated into the Plasma desktop, and it works well. Practical, versatile, extensible, full of goodies. But then, when I try to think of other candidates, my brain doesn't really throw any easy answers. Various Linux desktop did and do attempt to offer smart menus, but none of them really have that almost-AI super-tool. This led me on a pilgrimage, and what I found is a program called Ulauncher. Stop, testing time.
I installed Ulauncher using its omni-script, and this went fine. The first launch was terribly slow. After a few seconds, the launcher disappeared from the view, and I struggled getting it back. The reason was, all the excepted shortcuts were already in use - associated with Krunner. Yes, I was testing in KDE neon.
Before I could use Ulauncher, I had to open its preferences menu, and learn what the actual shortcuts are and then assign new ones. The actual menu comes with a spacious layout - and unnecessarily huge alpha borders. I cropped them in the image below, because they were 1) too big 2) captured background elements too - like the few pixels of the right border of the Home icon on the desktop 3) not symmetric, as the bottom border is bigger than the other three sides. Very inelegant.
Well, I started hammering at the keyboard, to see what gives. The one really practical thing - fuzzy search. You don't have to be 100% accurate, so even if you mistype or some such, Ulauncher will still most likely find the right application and not get stuck on one wrong letter. But then, there wasn't much I could do. The reason is - you need extensions!
Much like Krunner, extra functionality is available through third-party extensions. These are listed on the official site, and you install them by copying the URL of the extension (most likely GitHub repo) into the Extensions part of the Preferences menu. Once installed, extensions can be tweaked and used.
I went through the list and grabbed a total of five extensions, rather at random. Three installed fine, two did nothing and/or silently failed. Firefox Bookmarks does as it says. Extensions List is sort of a meta extension. The IMDb one disappointed me. I thought it would offer me inline results, but all it actually does is forward you to a browser and open a tab on IMDb, with the words you typed down. No different than searching through the browser using the IMDb search engine really.
The two extensions that didn't work include Duckduckgo and Windows Select. Now, this somewhat reminds me of styles and themes in Plasma (at least in past versions). You had integrated functionality to look for these, but then, some would 404, some would have multiple entries and you had to manually choose them, some would supposedly install, but then nothing would really happen. Here, I don't know why these extensions wouldn't install correctly, but 40% failure isn't a good thing on first run, especially since you do need the extras to actually make Ulauncher useful.
Overall, Ulauncher was somewhat sluggish. You can't ask natural math questions, like you would with Wolfram Alpha. I did try some basic calculations, and Ulauncher forwarded this query to Calligra Stage, which promptly crashed, go figure. Why not LibreOffice btw? After all, that is my default office suite. Oh well.
My initial impression with Ulauncher isn't stellar. It feels raw, unfinished and rather rough round the edges. It needs to mature and gain more stability, better responsiveness, and far more integrated functionality that does not depend entirely on extensions. The idea is to extend the basic capabilities - not replace them. A tool that needs a dozen other tools to work misses the point. Especially since the installation of extensions is a bit clunky (copy & paste of URLs), plus some don't work, and that ruins the overall feel.
That said, Ulauncher has a pretty neat, clean interface, the fuzzy search option is cool, and it gets the job done at the end of the day, even though it's still kind of an intern level type of job. I'd like to see Ulauncher become more powerful, with more inline functionality and a more robust extensions framework. Worth testing, but don't expect a revolution, because we ain't there yet.