After more than a decade of surveying iPhones, columnist Joanna Stern hands the reins to her generative-AI assistant to discuss Apple's latest

"It happens every year: Summer fades, kids shuffle back to school and I review the latest iPhones. But not this year. This year, I handed the job to AI. At least . . . part of the job.

We created Joannabot, a generative-AI buddy who never tires of answering your iPhone 16 questions -- especially whether it's worth an upgrade. With the help of engineer Brian Whitton and others, we fed it a decade of my iPhone review excerpts, Apple's iPhone specs and my notes from a week of testing the full iPhone 16 lineup. You can interact with it at wsj.com/joannabot.

Why a bot? Well, with iPhones, it's starting to feel very "Groundhog Day" -- similar, year after year. Plus, you might be looking for something my review didn't address. Joannabot is more open-ended. And since Apple is now all about AI, why not embrace it?

When you chat with Joannabot on your phone or computer, just remember this is an experiment. We told it to stay focused on iPhones, but like all generative-AI assistants, it can get things wrong, or make things up. To try the bot, you can also scan this QR code with your phone. It will take you to an online version of this article, with the chatbot:

For the bot to understand what I really felt about the iPhone 16 models, I had to give it my notes, based on my week of testing. Here's what my testing revealed:

Overall thoughts: The iPhone 16 Pro and Pro Max are the best iPhones you can buy right now. But the more affordable iPhone 16 and 16 Plus -- what I call the Regulars -- are more appealing than in years past. They now come with perks like the Action Button, Camera Control and Dynamic Island.

Plus, they offer better color options than the Pro. I love the blue color -- sorry, ultramarine. If my decision were based on color, I'd get an iPhone 16. But please don't choose an iPhone just based on color. You'll probably put it in a case anyway.

There are three reasons to spend the extra $200 and go Pro:

-- The third camera, with 5X telephoto lens, which I love for getting close-ups of my kids on the stage or soccer field.

-- The better battery life.

-- The always-on ProMotion displays.

Battery: The iPhone 16 and 16 Plus have solid battery life, lasting most people a full day on a charge. I'm not most people, so I opt for the Pro models. This year's smaller 16 Pro lasted as long as last year's giant iPhone 15 Pro Max.

I take my phone off the charger around 7 a.m., and on a busy workday (emails, calls, social media), the 16 Pro hit 20% around 6 p.m. The 16 Pro Max lasted even longer, not hitting 20% until 9 p.m. Over the weekend, I took it off the charger on Saturday morning -- and didn't have to charge until Sunday afternoon. Apple says this is the longest battery life of any iPhone -- and that's right.

Cameras: The iPhone 16 models never took noticeably better photos than the iPhone 15 . . . or even 14. And the new Photographic Styles, on-the-fly color and tone adjustments, were neat but not something I'd use often.

Video improvements are more noteworthy. I was able to isolate my voice from a train passing behind me using Audio Mix. And I enjoyed filming my toddler knocking down blocks in 4K 120-frame-per-second slow-mo with the 16 Pro.

The new Camera Control button isn't just for quick snapshots: Hold it down and you immediately record video. Oh, and I love being able to pause a video recording, though that's an iOS 18 feature available to older iPhones, too.

Other notes: The new wireless MagSafe charger (sold separately) is faster than the old one. It charged the iPhone 16 Pro Max from 5% to 50% in 40 minutes. But it's still not as fast as wired charging. Using the included USB-C cord, it took 25 minutes for that same charge. In both cases, the phone seems to get less toasty than the iPhone 15 and 14 models.

I did some initial testing of iOS 18.1, which includes Apple Intelligence, on the iPhone 16 Pro. The writing tools, which can help you rewrite text, are handy when writing emails or texts. Stay tuned. Too early to say yet if Siri is any smarter.

Bot methodology

Joannabot is powered by Google's Gemini Flash large language model. In testing, the more powerful Gemini Pro model produced better results but was cost-prohibitive to implement for this.

My colleague Brian Whitton did all the hard technical work. He built a system that would force Joannabot to answer questions based on a database of old review excerpts and a selection of specs from Apple's websites. When we realized the system needed deeper insight into my iPhone thoughts, I wrote a 12-page document with my explicit advice.

Together, Brian, myself and some of our talented editors wrote the system prompt to instruct Joannabot what it should and shouldn't answer. It behaves. . .most of the time.

I plan to share more on our experiences building a generative-AI bot trained on my years of hard work. In the meantime, please tell me what you think. Email me at joanna.stern@wsj.com." [1]

1. To Review iPhone 16, We Created Joannabot --- After more than a decade of surveying iPhones, columnist Joanna Stern hands the reins to her generative-AI assistant to discuss Apple's latest. Stern, Joanna; Whitton, Brian.  Wall Street Journal, Eastern edition; New York, N.Y.. 19 Sep 2024: A.10.