On iOS 27 with Siri AI, yes, it's conversational, no need to continually prompt it.
I've tried conversing with it while driving and it is just useless.
Trying to converse with it sitting down and with all the time in the world just doesn't work either.
My choices are basically: use the worst AI assistant in the world, use ChatGPT, or just google it myfuckingself. Siri will never win this one.
E: an example of a frustrating experience making it useless: I was browsing marketplace for used Mac minis and found one pretty cheap. I ask Siri, hey siri tell me about this Mac mini. It identified the model via the model number, but when I asked it for the baseline specs for that model it just kept regurgitating the information listed on the screen. The reason I was asking was because the listing didn't list the amount of RAM, so Siri was just unable to tell me, no matter how I phrased it.
What are your settings for Siri and which iPhone do you have?
Right now it's only supported in English, and your phone language/locale also has to be in English. Then you go into Siri settings and make sure it doesn't say it still needs to download Siri AI.
Also it's not supported for EU users (however Apple determines that) since Apple won't follow the DMA.