For starters, Assistant's iOS app is a confusing, disjointed, mess. You'd think the Assistant would be able to easily link up with all your other Google services, but that wasn't the case in my initial testing.
It isn't often that I agree with an article on Mashable. However, in this case I very much agree.
Using Assistant for iOS for a bit yesterday I found myself scratching my head thinking "but, I thought I could do this, or that, or that?". In reality, the Assistant on iOS as it stands is Google's search with voice input on top of it. Just like Siri. Which is equally frustrating to use.
One quick note here: Google does not have the access to iOS APIs that Apple does. For this reason Assistant is neutered from the jump. However, Google does a bad job explaining that and so user expectation is pretty high when I first installed the app. Assistant on iOS will likely never be as good as the Android or Home Assistant and that should be clear.
One other quick note: I think the entire tech industry began using the term "AI" a decade too soon. "Bot" is ok. A bot can respond to a set of commands and only those commands. That feels much more accurate when describing Google's Assistant. But calling features like Cortana, Siri, Assistant, Bixby (or whatever Samsung's assistant is) is a huge, huge stretch of the term AI in their current states. And likely will be for a number of years to come.