 There really aren't that many ways to change the iMac. It's already thin and light, though none of that really matters for a desktop. It's good looking, it's powerful, it's high resolution, it's not even terribly expensive for what it is. So how do you change the iMac? This year Apple picked one thing. One crazy high resolution thing. This is the Apple iMac with retina display. The screen really is the whole story here, and with good reason. It's a 27 inch display, 5,120 pixels wide by 2,880 pixels tall. That, if you're counting, is 14.7 million pixels. And they all look amazing. Blacks are deep, whites are bright, viewing angles are outrageous, colors pop off the laminated display. This is flat out as good a display as you will see on any computer anywhere. Having a resolution that high means a few things. One is that you get just an incredible amount of space on this screen. You can play a 720p video at native resolution, open a half dozen safari windows side by side, and have plenty of room left for Spotify and your calendar and your email. It's kind of like being in OS X's expose view all the time, except you can use everything. By default, the retina iMac runs at 2560x1440, turning pixels into what Apple calls points. Points are basically a stand-in for physical distance, which means everything on this screen is the same size as on a lower res Mac, but it looks better, because where you used to have one pixel, now you have four. That's why, at native 5120x2880 resolution, everything is hilariously small on this iMac. If you're using 4K video or a high res photo, the iMac is content aware enough to render that part pixel for pixel while still doubling everything else. Basically this is all a complicated way of saying that when you have the content to suit a 5K display, the iMac shows it accurately, and usually with space to spare. Otherwise it tries to find the middle ground to make everything a little more usable. That content thing is the sticky point of the retina iMac. Yeah, it has a 5K display, and yeah, that makes most things look amazing. Text is the big one, I can't get over how much I like reading on this thing. Games too, at least the ones that play at 2880x1440, look great. Bioshock Infinite looks incredible on this screen. 4K videos look amazing and play perfectly, and I love editing high res photos on here. But when you have pictures, and especially video, that isn't this high res, it can look really bad. Netflix doesn't stream in 4K on the iMac, and even at its highest possible resolution is fuzzy and soft. Same with Hulu, same with most of YouTube, and just about anything else you'll want to watch. Basically just don't try to watch anything that isn't 4K full screen, at least not while you're sitting just a few feet away from the iMac. Of course this happens every time Apple puts out a retina screen that's more impressive than the last one. It'll take the web and developers a little while to catch up and play at this higher resolution, but I think they will. You just might want to wait to pull the trigger on an iMac upgrade until then. The other thing that usually happens when Apple bumps up its resolution is that the first model is slow. It takes a lot of processing to power a lot of pixels. On my review unit, at least, that's not a problem. But I've been using the top tier model. It's crazy fast, consistent, and powerful no matter what you're doing. It even handles Adobe Premiere playback and editing, the things our video team work with every day, faster than just about any other machine. It's also of course $4,399. For a certain kind of person, that's a deal. It's certainly cheaper than a Mac Pro and a 4K display. But for most people, that's kind of the definition of overkill. The thing is though, I get the sense that the iMac with retina display needs just about all of that power to really sing. Even with specs like I have, videos will occasionally still stutter when I open a new Safari tab, and games will flicker or tear as I play particularly complicated scenes. Performance on the iMac is fantastic. Having this much solid state storage in particular is great. But I don't know how much room there is to spare here. Tread carefully with the bottom models. For $2,499, you get a 3.5GHz Intel Core i5 processor, 8GB of RAM, and a 1TB Fusion drive, which is part solid drive, part spinning drive. That's a lot of hardware, but it might not be enough if you're going to really put this thing to the test. If you just want Safari and Chrome and iPhoto and Spotify though, buy away. This is the best screen ever for using those things. It all runs underneath OS X Yosemite, the newest version of Apple's software, and one specifically built for a screen like this. There's lots that's new about Yosemite, but nothing specific to the iMac, though things like handoff and continuity might actually make a desktop more usable since it's so easy to take your work with you now. The insides are all new, but the shell of the iMac is still the same. It's the same thin silver aluminum shell that bulges slightly in the back and hides all its ports and looks good absolutely anywhere you put it. There's a Thunderbolt 2 port, four USB 3 slots, an SD card slot, a headphone jack, and an ethernet port. There are good sounding stereo speakers firing out of the bottom, but I'd still connect something external. It sits even on the same stand as ever. The hardware just hasn't changed here, and it didn't really need to. For some people, for some uses, the iMac with Retina Display is virtually perfect. I love editing photos on this computer, and I love just reading and browsing the web on it. This is a computer I want to use, but it's expensive. And it's really expensive if you want to take full advantage, if you want a machine that is as powerful as it is pretty. But make no mistake, Retina is the future of the iMac, and that is great news.