From a purely technical standpoint, the Smart Battery Case doesn’t offer as much extra battery life as competitors do. So in order to justify its $99 price point, it has to be “smart” in other ways. It has to build upon on existing Apple designs, and it has to utilize the iPhone's software. It does all of this. But I'm not convinced this is the best case.

The goal is to give iPhone 6 and 6S owners an Apple-branded battery life experience comparable to the one you’d get with the “Plus” phone models. That’s a nice proposition. On the other hand, it’s an admission on Apple’s part that the battery performance on iPhone 6 or 6S is a pain point for power users. For $99, that pain can go away.

What makes a smartphone battery case “smart”? It’s a question Apple is trying to answer with its brand new Smart Battery Case for the iPhone 6 and 6S . The $99 slip-on case, available starting today, is Apple’s challenger to Mophie and other companies that have offered similar battery cases for years.

I’ll start with design. Design is a big word, and it encompasses many things, and it is a religion at Apple, so maybe I should say "looks." The case has a bump. It’s the first thing you’re going to notice when you see it. And it’s not a look-at-the-way-the-lens-extends-from-the-body bump, it’s a my-iPhone-ate-my-iPod bump. It looks like you tried to shove a few too many credit cards and ID cards into the back of your iPhone case. The top and bottom of the Smart Battery Case hug your phone, which is supposed to offer a more comfortable grip when you’re actually using the phone. It’s a stark contrast from the solid curved back of something like a Mophie. This CASE HAS a badunkabump There are other elements of the design that I can appreciate. It feels nice. The whole thing is an iteration on Apple’s regular silicone case for iPhone, which has a lovely, smooth feel to it. There are soft pass-through buttons for volume and power, cut-outs for the ring / silent button and rear camera lens, and an acoustic port for the speaker. And the top part of the case is flexible, bending backwards and bowing out at the edges so you can slip the iPhone in, unlike some nail-breaking battery cases. It’s relatively easy to get the phone out, too. The case works just fine with Apple’s EarPods, but most other headphones I tried didn’t fit with the case on. They’d probably work with an extender, but Apple doesn’t supply one with the case. And, oh my. That bump.

There’s also the very straightforward matter of battery life. Even though the Apple Smart Battery Case costs twice as much as the $50 Incipio Offgrid Express, our pick for the best iPhone 6 battery case, and costs the same as Mophie’s Juice Pack Air, it doesn’t offer as much juice as these other battery cases do. The Apple Smart Battery Case has a 1,877mAh battery pack, while the Mophie Juice Pack Air is packed with a 2,750mAh battery and the Incipio Offgrid Express has a 3,000mAh battery. In fact, Apple’s Smart Case won’t even get you a full charge, from 0 to 100 percent. Charging with a Lightning cable is convenient Maybe some other stuff will appeal to you. Like the fact that Apple’s Smart Battery Case uses a Lightning cable, so if you already carry around a Lightning cable to charge your iPhone, you’re all set! You don’t need to pack a microUSB cable, too. Or the fact that this case is built with extra antennas to boost cellular performance, because the last thing you want — and Apple wants — is for your cell performance to be impacted by the case. In either, ahem, case, I didn’t have any issues with cellular connectivity while using the case.

Or, maybe you’ll like the way you can see how much juice the case has by swiping down on your iPhone’s home screen. This is pretty necessary, actually, because for a reason I don’t fully understand, the tiny LED indicator light that tells you whether the case is depleted (amber) or charged (green) has been put inside the case. Also, some other cases have physical buttons that you can switch off if you don’t want the pack to start powering your phone, so you can reserve the juice for later. Apple's Smart Battery Case doesn’t have any kind of button like this. Once you put the case on, it just starts charging your depleted iPhone. If both devices are at 100 percent, and you’ve got the case on, the phone will use the case’s battery first, then switch to draining its own cell.

Let’s say you don’t care about all this stuff. Let’s say you only care about real-life usage, like how long the case takes to charge and how many days you’ll get out of it. Last Friday, I put a totally dead iPhone 6S in a fully charged smart case, and an hour and 15 minutes later the case was down to 0 percent and the iPhone was 72 percent charged. (I was checking the phone’s display intermittently, so I probably drained the battery a bit while doing that.) It took under an hour to charge the case by itself with a 10-watt adapter (the kind that doesn’t come with your iPhone), and over two hours to charge the case by itself with a 5-watt adapter (the kind that does come with your iPhone). I got through the better part of a weekend with the case on my phone An iPhone 6S coupled with the Smart Battery Case is supposed to offer up to 25 hours of talk time, 20 hours of video playing, and 18 hours of web browsing over LTE. In real life, this lasted me through the good part of a weekend. I left home at 10 o’clock on Saturday morning with 36 percent battery left on my iPhone 6S, and popped on a nearly full Smart Battery Case (95 percent). The case began charging the iPhone. I went about my normal weekend, checking email and social media, looking up stuff on a mobile browser, and occasionally using the phone’s GPS. By Sunday evening, having not plugged my phone into a wall outlet all weekend, the phone had drained to around 2 percent. This was pretty great. So is leaving the house knowing my smartphone battery won't die by the end of the day. But again, there are other cases and packs that do this, too, and for less.