I currently run a google home and google home mini in my home along with chromecast's and chromecast audios (I retired my echo dot).
After the initial honeymoon phase I stopped using 3rd party actions and used my google home devices purely for controlling my smart lighting, power inputs and turning my Apple TV/ AV Receiver on and off via Harmony Hub and SmartThings.
Whole home audio works really well thanks to chromecast audios being able to convert my dumb speakers (varying degrees of quality speakers)...
So why am I interested in HomePod? The products potential in which I hope to see:
Apple TV voice control including iTunes content and live content.
Whole home audio for video content via AirPlay 2 (something you cant do without delay on google products).
HomeKit audio notifications e.g.: your front door has opened, unexpected activity on your security camera! Do you want to view on Apple TV?
Facetime Audio/ Accept normal calls between multiple HomePods/iOS devices (just like I can on iOS, WatchOS, MacOS (without hand-off).
However, what I need to see from Apple is a broader range of product in this field to compete e.g. Google Chromecast Audio competitor. I also need/hope to see an implementation of AirPlay that allows a AirPlay compatible AV receiver the ability to stream audio from a connected device like a games console back to HomePods.
I don't mind the fact that, at launch at least, I'll have to AirPlay Spotify to a HomePod but please find a way of implementing AirPlay so that my iOS device isn’t on lock down. Simply send the stream url to the speaker so I can take a call without interrupting the stream and the ambience created.
I'll be buying one on launch (I work in consumer tech support) but it'll be a while before I honestly think it'll be worth purchasing for normal consumers. Time will tell but I'm looking forward to the journey (provided HomePod evolves beyond what I mentioned).