It's cool precisely because it's useful! Have an expensive computation task? Just dump it onto the cloud instead of running it locally. This is probably the most streamlined way to do this that I've ever seen.
Especially nice for spinning something up with zero overhead. Maybe not optimal for production apps. Maybe good if you're constrained on server resources but less so on budget. Maybe good if you're still on the Lambda free tier pricing.
Essentially, this can help offset the need for managing extra servers for those kinds of tasks.
There's nothing mystical about this. The source code is 4 files, which I read. It sends your function to Lambda, and that's cool, and the syntax is really elegant. Enough that I could totally see throwing something together using this to solve some complex problems without really thinking about it.
I don't think this is all the way there, but I really like the idea of programming with APIs like this being as easy to use as language libraries.