I've had several iPhones for years, but in all that time, I've never used Siri, and I think I may have used Alexa once. It's not that the software is bad, or doesn't work well (I honestly don't know!), but rather something more fundamental -- I don't want to talk to my devices. This may seem like a strange position to take, especially from someone under 40 who works in the tech industry, but when I stopped to examine why I don't want to talk to my devices, I realized something interesting.
Talking to my devices feels awkward because I have to dumb down my interface.
Computer software, including user interfaces, is highly deterministic, because that's how computers work, and how we expect them to work. Given the same inputs, we want the same outputs (unless randomness is part of the program). A key is pressed or it is not. A button is clicked, or it is not. Interfacing with computers would be immensely frustrating were this not the case, and indeed it is frustrating when it appears so because of some hidden state we are not aware of. Moreover, for ease of use in providing a deterministic, unambiguous interface, we specifically design out interfaces to be as simple as possible, such that it's easy to get the computer to do what you want it to.
Human language, on the other hand, is not only extremely complex, but it is also rife with ambiguity. It takes humans (who have evolved for precisely this sort of thing) years to master the interface of speech, to hear sarcasm, innuendo, puns, figurative language, etc. Speech is a rich, vibrant thing, but to use it as an interface to a computer program, one must dumb it down and strip it of ambiguity so that the program works as people expect. This isn't bad, it's not a misuse of our speech capabilities, but gosh, to my ear, it's so awkward. It feels like the wrong tool for the job, like whatever I'm doing with my devices, it's not talking, exactly, but merely giving vocal commands. I'm using my voice, yes, but it sure doesn't feel natural.
This is not to say human speech interfaces are inappropriate for computers, and it's certainly possible that my feelings would be different if I had grown up with them, but until they get good enough that I feel like I'm having a conversation with anyone else (perhaps Siri needs to pass a Turing Test?), I don't think I'm going to be using them.