 How thin is a smartphone supposed to be? How thin can it be? I can't imagine the answer is much thinner than this, though I've been wrong before. This is the Oppo R5, and it is the thinnest smartphone in the world. For the moment, anyway. The R5 is 4.85mm thick, not counting the bump on the backside of the camera. It's almost exactly the size of five credit cards stacked on top of one another. It's really, really, really thin. Just by way of comparison, the iPhone 6 is 6.9mm thick, which is fully 40% thicker than the R5. The original Motorola Droid Razr, the one that was supposed to be so thin it could chop the world in half, was 7.1mm thick. That's basically gigantic next to this thing. For the most part, otherwise, the R5 looks as if you took an iPhone 5s and just stretched it out. It's made of really nice, really sturdy chamfered metal, and despite being this slim, doesn't feel breakable at all. It has white stripes on the back for all the antennas, and a glass white panel on the front. It's almost uncomfortably thin, but it's also really impressively made. The R5 is so perfectly Oppo in a way. Oppo is one of China's fastest growing phone manufacturers, and it got there in large part by taking one feature and just blowing it out through the ceiling. When it launched the R5, it also debuted the N3, which has a 16 megapixel camera that swivels automatically so you can take higher resolution selfies than you will ever want to have in your life. It's clever, it really is, but it's also sort of insane. It's also insane that the R5 is so thin, especially when it didn't need to be. And being this thin even causes a few problems, like the fact that there's literally no room for a headphone jack, so you have to plug in the headphones with a USB adapter. Oppo made this phone to prove something, not necessarily to be the perfect phone for everyone. Which it's not. The R5 runs Android 4.4 along with what Oppo calls ColorOS 2.0. Basically it's a bunch of customizations to Android, some of which are pointless and some of which are actually really cool. There's a drawing menu that you get to by swiping up from the home button, which lets you scribble a note or write symbols to open apps. It reminds me of my Palm Pilot from back in the day and I love it. A lot of the changes though are just ugly customizations of Android, and there's a theme store that tells you to enjoy your individuality by theming your phone like, I'm not making any of these up, fruits candy, or colorful line, or wolf falls in love. It's weird and I don't get it, but so it goes. The best thing about the themes is that one of them just looks like Android. Beyond all that, there's really not much to say about the R5. It's somewhere between mid-range and really high end with a 5.2 inch 1080p screen, a 13 megapixel camera, a Snapdragon processor, and 2 gigs of RAM. It works pretty well from what I've tested, though the battery life doesn't seem to be very good. I guess that's not surprising. This phone is tiny. It's the thinnest smartphone in the world, at least until something else comes along. And somehow I don't think that'll take very long.