Sony also packs the phone with several camera apps that can be useful — when they work.
The waterproofing should give you some comfort using the phone in the rain or taking a selfie in the pool, as long as you keep the ports covered with the attached plastic seals.
Just don't expect extensive operations underwater, as the touch screen doesn't work when wet. You can continue video and music you already have going, but you can't start new ones. Same with voice calls. Sound quality through the external speaker suffers.
Fortunately, you can use headphones. Sony's water-resistant Xperia Z phone last summer had a headphone jack that needed to stay covered. There's no need to cover that in the Z1s, so you're protected even when you use headphones. Your headphones might not survive, though.
The Z1s also fixes a shortcoming with the Z. You can set the volume button to trigger the camera shutter for shots while snorkeling. The Z's touch-only shutter has to stay dry.
The camera's high-megapixel count means more details get stored, which is important for cropping and printing. However, megapixel is just one factor.
At the U.S. figure skating championships in Boston over the weekend, photos of skaters from my nose-bleed seats came out average for a phone. I noticed more details in some of the banners across the arena, but a larger factor was how much my hand was shaking when I snapped. In a few of those shots, colors were completely off.
The camera's Social Live app lets you stream 10-minute video clips live on Facebook. You can choose who can view them, though it doesn't recognize groups you have curated on Facebook, such as "close friends" or "family." If you're willing to click on names one by one, or share with everyone, it's a fun tool for weddings and other shareable moments.
Another app, called Info-eye, gets you more information about a book, wine bottle or landmark after you snap a photo of it.
Results were mixed. It took several tries for the camera to recognize the Empire State Building in New York. Initially, I got weather and nearby restaurants instead. The camera recognized only about half of the books I snapped and needed two tries to recognize my wine label.
The app is also supposed to recognize QR codes, the square patterns that direct you to more information on the Internet. But I got it to work only once out of at least 17 tries at the MIT Museum in Cambridge, Mass. Most of the time, the image came out too blurry, or the phone tried to scan surrounding text instead.
The Z1s catches up to Apple's iPhone 5S in two ways: You can snap up to 10 shots per second in a burst mode, and you can see how an Instagram-like special effect will look before you snap the shot.
There's also a Timeshift Burst app that lets you snap even more shots — 61 in two seconds. It's easy to pick the best shots by scrolling through the images like a flipbook, but the app limits you to two seconds.