Microsoft Surface Pro X Todd Haselton | CNBC

Microsoft's Surface Pro X is the company's latest attempt to sell a computer that runs on an Arm-designed chip like the iPad and most cellphones, instead of the Intel-designed processor akin to the ones that have run most Windows personal computers since the very earliest days of personal computing. The idea is that this computer, which runs on a custom Microsoft SQ1 processor, built in partnership with Qualcomm, can deliver a really thin design with no fans, long battery life and cellular connectivity, while also running most of the traditional Windows apps people need. I've been testing it for the past several days. If this all sounds a bit familiar, that's because Microsoft has tried this same strategy before, first with the Surface RT computer in 2012 and again through a partnership with Nokia in 2013. Last year, I reviewed one of the first modern Windows on Arm computers built by HP and found that it still lagged behind Intel machines. Microsoft has made some improvements in the Surface Pro X, but it's not quite fulfilling all of Microsoft's promises. Since it doesn't run on a traditional Intel or Intel-compatible Arm processor, some of the apps you might rely on for work may not work. Because of that, and the $999 starting cost without the $139.99 Microsoft Type Cover keyboard, I don't expect this to fly off store shelves. Still, it's the best attempt yet at a new kind of Windows computer. And it's got a nicer design than the Surface Pro 7, which still uses an Intel chip.

What's good

Microsoft Surface Pro X Todd Haselton | CNBC

I love the design of the Surface Pro X and wish Microsoft used the same big display with narrow edges on the new Intel-powered Surface Pro 7. The screen is big, bright and sharp. The speakers are great. The form factor is similar to the Surface Pro 7, too, with an optional keyboard (it costs $269.99 with the optional Surface Pro Pen or $139.99 without it) that attaches to the bottom and allows the tablet to double as a full laptop. This year, Microsoft hid the new Surface Pen inside the top of the keyboard in a tiny pocket where it charges. It's a bit of genius, since this little area also makes it hard to lose the pen in a bag. The device is thinner than the Surface Pro 7 but has a similar kickstand that pops out from the back to help keep it sturdy.

Microsoft Surface Pro X Todd Haselton | CNBC

A small panel in the back opens up allowing you to swap in more storage or pop in a SIM card. I added a T-Mobile SIM and had cellular connectivity in just seconds, something that you can't do with almost any other computer on the market. This lets you connect to the internet when you don't have Wi-Fi. Microsoft's Windows Hello, a facial recognition system that lets you unlock the computer, continues to impress me. The camera identifies my face and unlocks the computer right when I sit down, almost instantly, similar to how I unlock my iPhone and iPad. It means you don't need to spend time typing in a long password. I also love that it charges fully in just an hour — my MacBook Air takes about 3 hours to charge. And, if you want, you can use a USB-C charger instead of the included power brick, which is convenient for people like me who want to carry a single charger for multiple devices. OK, so the elephant in the room: Windows 10 on Arm. I've been a big critic of this approach in the past, since I really don't like having to think about whether an app is going to work on my computer or not. But, Microsoft has done a good job adding support for older apps. It's not perfect yet, but it's getting there.

Microsoft Surface Pro X Todd Haselton | CNBC

I was able to download and run most of what I use regularly. Spotify and Netflix are in the Windows Store (though those usually work just fine in a browser anyway). The Google Chrome browser downloaded and worked flawlessly. Microsoft Office is, of course, available. I even tried running a game from 1997 called Ultima Online that wasn't designed to work on an Arm-based computer. Microsoft, in this case, runs those older apps (technically called 32-bit x86 apps) in an emulator. It's seamless, and you don't even realize they weren't supposed to run on this machine. Some apps you might need for work or school still don't work yet, however. Let's talk a bit about that.

What's bad

Microsoft Surface Pro X Todd Haselton | CNBC

Windows 10 on Arm generally looks and feels like Windows 10 on any other computer. But it isn't the same as the regular version of Windows 10 that most apps were designed to run on. That means you might run into trouble, as I did, if you need a specific app for corporate VPN access. The app I needed didn't run on the Surface Pro X. You should make sure your school or office will let you connect first. Then there are other apps that just don't work. Adobe's Creative Suite, which includes Photoshop, doesn't run on the Surface Pro X. It might eventually, since Adobe just launched Photoshop on the iPad, but it's not here yet. If you rely on specific 3D rendering, financial or video editing apps, you should make sure they're supported before you buy the Surface Pro X.

You'll see this error sometimes if your app isn't supported. Todd Haselton | CNBC

There isn't some single universal web site you can just go check to see if they'll work, either. You just need to try installing them one by one to see if they fail. Or, you can try to teach yourself a bit about 32-bit x86 and 64-bit x64 compatibility and check to see if the apps you use will run on this machine by visiting each app's website. In some cases you won't find the information. The problem here is most people buying a new computer assume it's going to run every Windows app just fine. People considering the Surface Pro X need to know that's simply not the case. I also have a few quibbles with the design.

Microsoft Surface Pro X Todd Haselton | CNBC

One of the big promises of using an Arm machine is all-day battery life. But the Surface Pro X didn't seem to last any longer than my MacBook Air, even after promising up to 13 hours of battery life. After using it at my desk for a couple of hours with the screen at half-brightness, it dropped down to 86 percent battery life. That's not really all-day battery. But it was able to idle without draining much, which is good if you're worried about the battery draining while it's in your bag. The keyboard is just OK. It's mushy when you press down on it and flexes a lot, which is expected on portable like this. I still prefer the sturdier feel of the one on Microsoft's Surface Laptop 3. I like that the keyboard is backlit, though, and I like the large and clicky (albeit loud) glass trackpad, too. Finally, the Surface Pro X's kickstand is still terrible if you want to use the computer in your lap. I felt like I was constantly trying to balance it.

Should you buy the Microsoft Surface Pro X?

Microsoft Surface Pro X Todd Haselton | CNBC