I can admit that I'm misplacing my rebuttal, but plenty of people are angry. r/Android is a hot mess right now, the butthurt is so strong there right now.
But in this thread, we are the only two that have stated to have actually even used it. All the "outrage" is what's been killing Allo, not anything else. Like you said, it's a messaging app. It does its job well. The only feature I want/need in order to fully make the switch is a web client. The AI is fun enough, stickers are nice, drawing on pics can be fun, message resizing is fun. It's faster and smoother than hangouts. I said fun a lot. That's the point.
But whatever. Google is late to the game, but I like what they put out. And unlike hangouts, I see Allo getting better with time.