Even though the technology is starting to look a little behind the times in these days of ProMotion screens and OLED smartwatches, I still really like E Ink. There’s nothing quite like it for outdoor visibility, and even away from sunlight there’s something to be said for a display that doesn’t suck much power or blast light in your face.

It would seem natural, then, to want a way of applying these benefits to smartphones. The YotaPhone, an Android phone with a secondary display on the back, is the most advanced example of this so far, and there have been a few efforts to develop iPhone cases with similar functionality — a company called Popslate recently shut down after hitting problems with its latest model.

This leaves Oaxis as the most prominent company iterating on the idea today, and I’ve been testing its latest product, the InkCase i7 Plus. It’s an iPhone 7 Plus case with a 5.2-inch E Ink screen that can be used to display widgets, ebooks, photos, and so on. As far as I’m aware, this is the largest E Ink screen in a product like this yet, so I was looking forward to testing it out. Would it stop me needing to take my Kindle to the beach?

On the plus side, the screen looks great. It takes up most of the back panel, which means that the very least it can do for you is offer a completely customizable case that you can switch up every day. The picture you see on the case above is one I recently took in Taiwan, for example. Oaxis has also considerably shrunk the InkCase logo down from the oversized one seen on the regular iPhone 7 model, which goes a long way to making the case more palatable.

Unfortunately, the InkCase itself is still pretty bulky, and I don’t find it very comfortable to hold. The back panel’s sharp raised edges are presumably designed to protect the E Ink screen when resting on a surface, but the rubberized material just feels cheap. The case also makes it pretty much impossible to access the iPhone’s mute switch, and the power button is the worst button I’ve used in a long time — it’s stiff, unresponsive, and super thin, so you have to press your fingernail in for a few seconds each time in the hope it’ll actually work.

You’d have to really be okay with the tradeoffs

I should say right away that I usually don’t use cases on my phones at all, so the InkCase’s bulkiness will seem a little more pronounced to me. If you’re used to using cases that focus on protection, the InkCase probably won’t seem that big at all, and you can of course get a lot of extra functionality out of it. But for me, something like this would need to go a little further to justify its extra size, weight, and inconvenience.

And there are lots of little inconveniences. The InkCase communicates with the iPhone over Bluetooth and charges using a fiddly proprietary magnetic connector, which is unfortunate (though the battery is yet to run out after a week of use). You can sync ebooks, news articles, and items from your Pocket queue over to the case, but the iOS app is poorly designed and requires a lot of fiddling to get things to happen. And once you do get files onto the case, reading them isn’t as comfortable as it ought to be — you have to use pokey capacitive buttons below the screen, which means you can’t easily turn pages when holding the phone in one hand. The E Ink panel itself isn’t touch-sensitive, making it extremely tedious to scroll through long lists with the buttons.

Still, if I were fine with the other compromises inherent to using a case of this size, I might use the reading functionality to save battery on a sunny day sometime. And as protective cases go, it’s pretty cool to have one that can change up its look every day. But at an early-bird Kickstarter price of $99 or $159 normally, you’d have to really be okay with the tradeoffs to make the InkCase i7 Plus worth it.