My experience is like yours. For what I do, Play-Fi streaming works. My challenge is getting comfortable with its extremely odd interface. Here's a perfect example:
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This screen automatically appears whenever I stop play on a device, or when I want to switch a playing device to a different source, so I see it a lot. Set aside that the screen is embarrassingly unattractive. What is a zone and why am I told how to create it? After swiping in all directions (does nothing), trying the normal android back and home gestures (does nothing), hitting the Play-Fi logo (does nothing), I realized that hitting the "+" was the only option. I have to hit "+" and then "create zone" to get back to the home screen that shows your devices. It does not create a zone...just gets you back home so you could. Since that seems to be all it can do...why not just return you to the home screen automatically? Let me know if I am doing something incorrectly.
The good news may be that proprietary interfaces....both bad ones like Play-Fi and arguably good ones like Sonos, are becoming much less relevant as everyone races to compatibility with Google & Alexa control. Play-Fi is rapidly expanding Alexa control options, but Alexa control does not seem to work for a lot of functions so far. I hope they can improve that, or allow more direct "Casting" from apps besides Spotify.