I'm not usually a fan of smartphone cases. I prefer to keep my iPhone sleek and bare, but PopSlate may just convince me to finally suit up. After spending a week with the company's new E-Ink iPhone 6 case, which allows you to display images on the back of it, I came away pleasantly surprised, even if it's still missing some key features. Still, for $129 it may not be worth your case-buying money, at least not yet.

First and foremost, PopSlate is a lot of fun. It's super easy to snap a photo or grab one online, and then flip it onto the back of your device using the official app or even straight from the photo gallery. You can store up to eight images on the case itself, and each time you add a new one the oldest picture gets wiped automatically. The entire process is simple and intuitive, and it only took me a few minutes to get comfortable.

Managing your photos can be tricky though, and there's no easy way to delete a specific image. PopSlate says it eventually plans to add the ability to manage your stored pictures from the app, and even upload multiple images at once. But for now you'll be stuck cycling through all eight, one at a time.

Not every image looks great on a 4-inch E-Ink frame. I quickly found that simple cartoons and graphics worked best, while more detailed pictures generally turned out kind of blurry. Of course, you can still share you selfies with the world using PopSlate if you want, but the image that shows up on the back of your phone may not look particularly flattering,

PopSlate can also be pretty handy. Several times over the week I used to it to save a Google Maps screenshot after looking up directions. Riding the subway in Manhattan, I was able to check my route underground without a cell signal. Earlier that week I tried the same thing riding my bike, which made it possible to quickly glance at the directions while stopped at an intersection without needing to unlock the device and launch Google Maps.

I'm not sure how useful PopSlate might be while driving. Your Google Maps route for longer distances probably won't be very legible on the E-Ink screen, though you could always take a screenshot of the turn-by-turn directions instead. It's also great for storing your boarding pass or any other sort of mobile ticket, though that didn't come up during my week with the case.

That's about all PopSlate can do for now, though the company has big plans for the future. In about two months, the case should get support for If This Then That (IFTTT), making it possible to automatically upload anything from the daily weather report to sports scores directly to the back of your phone. Later this summer, PopSlate plans to open up its API entirely, offering direct access to any interested third-party apps. Once those features arrive PopSlate will be pretty awesome, but for now it feels incomplete.

From a design perspective PopSlate is good, if not great. It feels nice but adds a ton of bulk, practically doubling the iPhone 6's thickness, and I'm a little worried what the upcoming iPhone 6 Plus version will look like. The soft plastic also picks up smudges pretty easily, at least on the black review unit I was given. There's also a white version, which probably won't attract as many fingerprints.

The battery is great, and lasts for days or even a full week on a single charge. The Bluetooth connection can be a little spotty though, and I found my phone would sometimes lose track of the case for no clear reason. Re-syncing only takes a few seconds, but it can be annoying when it drops unexpectedly. That's a small complaint though, and I'm sure it's something PopSlate will eventually fix.

But that's my real issue with this case. It's easy to see PopSlate for what it could be and get excited, but the current version becomes a bit of a letdown by comparison. It's tough to review a product based on features that still haven't arrived, and once the company rolls out everything it's promised, I'll feel more comfortable recommending this case. For now it probably isn't worth that high price tag, even if it's only a few months away from some major improvements.