Early reviews raved about the HomePod’s sound quality, and that clinched it for me.
I am in the same boat as Jack. Pre-ordered a HomePod and two days in, I love the sound quality -- HomePod sounds great soft or loud, with any genre of music, and as an upgrade over the built-in TV speakers when using Apple TV. As far as the "smart" half of the speaker, my needs are simple beyond music: control our HomeKit lights, set timers, add things to Reminders, play podcasts, and tell me the weather forecast. From everything I've read on actual smart speaker usage, those are the only reasons most people use smart speakers.
Of course, Alexa and Google Home have a different M.O.: Google as an index of all knowledge on the web and Alexa with a wide library of skills. I do have an Echo Dot and while the breadth of the skill library is impressive, a vast majority of the skills have very limited use cases. It is like shopping on Amazon, you know you can get almost anything there, but you keep buying the same small number of things you actually need. In the end, I used the Echo Dot for all the same reasons I use HomePod and the Echo Dot speaker is not even listenable.
The biggest miss with the HomePod is access to a calendar and multi-user recognition, but I'm sure that will come sooner than later. That's the thing -- the "negatives" are all software/services related and can be fixed with some software updates. The hardware is flawless.
Not to mention privacy: I'd much rather trust a smart speaker with the privacy model of Apple and the HomePod, than Google and Amazon -- two companies looking to sell me something or sell me to advertisers... or both.
Long story short, I highly recommend HomePod if you are an Apple Music user. As of now, the HomePod only makes sense for subscribers. For the rest of you, I'd wait for those future updates and scoop one up without delay.