Well, I´ve done a bit of testing after updating to 15.3 with my living room OG stereo pair and so far I am impressed.
Sound wise it seems that the overall muddy sound signature with recessed mids and overbearing messy bass of tvOS 14/15 its finally gone. So much clear and balanced.
No popping, no Airplay issues. Siri requests are faster than ever and overall the whole interaction with the speakers seems super responsive and fast now, like it should be. And she actually stays at the voice volume level that you tell it to in subsequent interactions, even with "automatic Siri volume" toggle enabled in settings, which is great.
There is just one area that unfortunately seems the same as previous tvOS 15 firmwares, and that is Homekit. There Siri still lags "one sec, I´m on it" a lot although for me it always carrie on with the scene at the end which is a huge improvement over previous firmwares. It just take a long time to do so and lags, but at least she get it done now.
Frankly, given the ******** that the homepods software/user experience has been since 14.6, I´m very happy with the update.
Better late than never to show some care for the homepod platform, I suppose. This makes me hopeful of future firmwares.
Today with more free time I have continued the testing.
Lossless playback is still not bug free, unfortunately. The old bug that randomly causes loud static after 15 seconds of playing a lossless track on IOS and Mac OS is to my dismay present in tvOS 15.3 (I´m talking about the homepods, not the apple tv. The Homepods use a fork of tvOS).
Disabling lossless in the home app settings, of course, fixes this, along with a strange old radio interference sound, sort of a very faint crackling/popping -not to be confused with the homepod software/hardware popping issues-, that from time to time emerges during the playback of a lossless album.
This two lossless related bugs I have experienced them quite a bit on Mac OS and IOS since lossless was launched last summer.
I dont, for the life of me, understand what can be so complicated logistically about streaming an ALAC file, and why these issues have not been completely erradicated many months later yet.
Also the old homepod related Atmos bug is still present on 15.3. The Homepods will play the Atmos tracks by default automatically, even if the Dolby Atmos toggle is disabled in the home app settings.
What you need to do is to force closing the home app on your IOS device, open it again, and enable Atmos.
Then force close it again, open it, and disable Atmos. It will stay disabled for good forever (even through software updates)... until you factory reset the homepod again.
If you do, the homepod will play Atmos tracks by default despite the setting being off in the home app, and you will have to repeat all the steps indicated here to truly turn it off.