I've been using a small board called the Oak from digistump for deploying arduino home-automation devices around the house. The Oak is a great board with good wifi, but the Particle firmware has always been trouble: difficult to set up, random flaky behavior, etc.
At heart the Oak is an ESP8266 chip, and these days there's a lot of independent support for ESP8266. So when I found some notes in the Oak forum about removing the Particle firmware and using the ESP8266 core directly, I jumped at the chance to try it out.
It has worked out very well. I first tried this in the summer, and my first ESP8266-core Oak has been running without any problems for several months now.
Besides the easier board initialization & smoother development, it has also been really nice to have a simpler tech stack to work with. I no longer have the Particle cloud in the mix, which used to keep a connection to their cloud service alive.
Some of the Particle functionality was really nice when I was getting started. But the setup complexity & reliability problems were just too much. And now there are good alternatives available to the Particle functionality, most of which I can use locally instead of in the cloud, there's nothing special that Particle offers anyway.