I kind of hate the idea of Electron, and this is for a variety of reasons:
* I think HTML/CSS is a terrible language.
* I think the web is too bloated as it is, and extending that paradigm to the desktop only encourages more lazy, bloated development.
That being said, I get the appeal Electron has for a lot of people. If you already know web development, then writing a desktop app becomes a no brainer. If you're already a destkop UI guy, you can learn Electron and be a web front end guy too. All good things.
But the idea of using a fucking gigantic framework (I mean think about it, just Electron by itself is all of Chromium basically, or at least the big complicated exciting bits) is a massive code smell to me. It's like using an ORM or a heavyweight web framework: whenever you're leaning on that much code just for your baseline of functionality, you're making a lot of assumptions that should, as a developer, at least give you pause. One of the things I love about Swing is that I can spin up a basic prototype in a couple hours with just a couple hundred lines of <insert non-java JVM language here>. And besides the built-in language UI framework, I own every piece of that code and can tell you what it all does. I feel like web development (an by extension, Electron) doesn't have any of those desirable attributes.
Now, there is one exception to all of this: one of the apps someone on my team supports at work is our monitoring dashboard/customer service portal. Because of some bizzar-o rule from up top, we aren't allowed installing anything except for absolutely essential apps on the support machines. Electron proved to be a lifesaver here because we could wrap our web-based portals in "desktop-y" apps and get rid of the web browser entirely. For cases like that (or like a friend of mine, who is currently working on medical instrument displays and uses JS/Electron in a couple of experimental projects because it's easier than Qt and the machines run Linux or Windows 7 anyway) where really what you need is a website, wrapped in a clean sandboxed container, I can kind of understand its niche.
This is by far the most powerful 'feature' of Electron, to take a largely already written webapp and insta-package it into a cross-platform desktop application.