Depends upon what you want to do with it. Personally, I'm not overly impressed so far... but that could be because my imagination for what Siri AI should be capable of, exceeds both what Apple promised and what the technology is ready to do right now. It is somewhat better than the previous version of Siri, at some things.
One area where it commonly fails is pretty nearly anything related to Music and playlists.
I asked Siri the other day to count the number of songs in the active playlist -- an easily discoverable piece of metadata -- and it gave me a wrong answer; the playlist in question has over three hundred tracks and Siri claimed it was something like 130. My first thought was: maybe that's the cap on how many tracks Music can recognize and shuffle -- which is an actual issue I've observed in the past.
So, I tried changing the context a bit, and opened the playlist in question so that it was right in front of me and clearly in memory, and asked again. Siri said five. I'm like, "Do what, now?" I looked at the screen and realized that this was the number of tracks displayed on screen. The screen awareness feature had kicked in, and it got the answer wrong this time for an entirely different reason. I tried a third time, with the playlist scrolled all the way to the bottom, so that the actual count was displayed on screen... and received yet another wrong answer. (I don't recall what that last answer was, offhand.)
Edit: I went back and tried it a couple more times just now, so that I could file my bug report via the Feedback app. To my surprise, this time when I redid the "scroll to the bottom so the count is on screen" test... it got it right! Then, just to add a bit of irony to the whole tale, it somehow failed to log that last correct answer to the Siri conversation history. (Womp, womp.) I still added the screenshot of the history to the feedback report, but also added a comment about the missing conversation. Weird stuff.
So yeah... Siri AI certainly has some peculiar limitations, which Apple still needs to work out.