Sitting on a bench in downtown Boston, I’m uploading and downloading files like a madman on the world’s first 5G laptop, the aptly named Lenovo Flex 5G. I can download Spike Lee’s new movie Da 5 Bloods from Netflix in under 30 seconds versus more like half an hour on regular wireless connections.

Wireless carriers have been promising amazing download speeds and other tricks from their new 5G networks, which are supposed to be 10 to 100 times as fast as the average 4G LTE connection. But it’s been a mixed bag so far.

The Flex 5G changes the equation.

For one, 5G on a laptop is a lot more useful than 5G on a phone. The first 5G phones are pricey—typically $1,000 or more—and aren’t used much to download files now that almost all video and music is streamed.

But on a laptop, there are all kinds of files we want to access, from high-resolution photos to graphics-packed PowerPoint decks to big data spreadsheets. Grabbing them from cloud storage, sharing them with coworkers, and updating them with fresh information all benefit from speedier 5G service. People also use their laptops for powerful web apps, like the online version of Adobe’s Lightroom photo editing software. Those apps work much better with fast connections.

And what a connection I have. On this bench, admittedly in one of the few areas in Boston where Verizon’s superfast 5G is available, downloads on the Flex 5G average more than 1.5 gigabits per second. That’s almost 50 times as fast as the average 4G download speed in the U.S., according to market tracker Ookla, and speedier than almost everyone’s wired home Internet connections.

I used the laptop to download a huge PowerPoint file from the web just by clicking on it. No delay whatsoever. Then I downloaded a dozen highly detailed photographs from my cloud storage provider at full resolution and attached them to email, again with almost no wait.

When I sent off the email, however, there was a much longer wait. Verizon’s 5G network in Boston only does downloads, not uploads. My average upload speed with the Flex 5G on this bench? A paltry 50 megabits per second, no faster than 4G.

So this is the part of the review where we must note that even if you buy this brand-new, $1,400 superfast 5G laptop, there are few places—very few places—where you can actually use it on 5G right now. Verizon, the exclusive carrier for the Flex, offers 5G in parts of 35 cities, with a goal of hitting 60 cities by year-end. But even in those cities, the 5G network covers a tiny fraction of the region. Verizon customers found 5G connectivity only 0.4% of the time in the U.S. in June, according to the latest report from Opensignal.

Here’s most of the Boston coverage map, for example (the darker red areas indicate where 5G coverage is available):

4G LTE

Even in the coverage areas, connections can be dicey. At one point, I moved to a nearby bench and ran a speed test. The laptop dropped the 5G connection and reverted automatically to 4G. The speed? Just 98 megabits per second.

On the other hand, I’m not generally walking around while using my laptop. Spotty 5G coverage is a much bigger problem for phone users on the go. If I could sit in a café with Verizon 5G coverage and use the Flex 5G, post-pandemic, I’d be all set.

In addition to buying the laptop, for $1,400 outright or $58 a month for 24 months, Verizon also requires a separate monthly connection fee for the device. It’s $30 a month for 5G service if you already have a wireless phone with the carrier or a heady $90 per month by itself. Cheaper plans are available with 4G connectivity, but that defeats the purpose of getting the Flex 5G.

In most other ways, the Flex 5G, which comes in one undistinguished color, “iron gray,” is a standard if expensive business laptop. It weighs almost three pounds and has a bright and sharp 14-inch touch screen that could be a tad brighter for outdoor use. The keyboard is adequate, with a little bit of mushiness when you strike the keys and not as much travel as Lenovo’s top-of-the-line ThinkPad laptops.

There are two USB-C ports and a headphone jack, but nothing else, so don’t forget your dongles. The screen can fold back to turn the Flex 5G into a (very heavy) tablet. And for its price, some of the specs—only 8GB of memory and 256GB of storage—are underwhelming.

There is one additional Flex 5G feature that sets it apart from competitors, and is both a big benefit and a big downside. The processor in this Windows laptop isn’t made by Intel or AMD. It’s a Qualcomm chip based on designs from ARM, meaning it has more in common with smartphone processors than typical PC chips.

The big benefit is battery life—insane battery life. I worked all day on the Flex 5G, running numerous speed tests, downloading lots of files, and generally pressing it to the limit. At the end of the day, the battery was still more than half full. Lenovo claims 26 hours of battery life, and I believe it. That’s a tremendous advantage for people working away from the office, as we almost all are right now, and on business trips, which almost none of us are on.

But with this amazing power comes a great limitation. Like Microsoft’s Surface X tablet, the Flex 5G cannot run all regular Windows apps. Microsoft has ported all of its apps. And every web app that I tried, from Slack to Gmail to WordPress, worked just fine. But if you want to run Adobe Photoshop, Affinity Designer, or many other popular Windows desktop productivity apps, you’re out of luck. Major video games also don’t run on ARM chips yet. Microsoft has a website that details some of the challenges and potential fixes for Windows apps on ARM devices.

Still, more app developers have been making their apps compatible. Cisco’s AnyConnect VPN app, a native Dropbox add-on, and some other business apps that were the subject of user complaints last year related to ARM devices are now available in Microsoft’s app store for the Flex 5G, and they install just fine.

The problem with the Flex 5G, despite its light weight and incredible battery life, is that it can only grab 5G service in limited locations right now. And users may have trouble trying to use apps that aren’t compatible.

In this case, it may pay to wait for 5G service to become more ubiquitous and for more Windows ARM apps to become available before switching to the Flex 5G.

Dell and HP also have 5G laptops coming soon, and it may pay to wait and see how they compare with the Flex 5G (particularly the HP model, which is supposed to run on a more typical Intel chip).

But no matter the limitations today, the future is becoming increasingly clear. If you are doing business on your laptop, or playing highly detailed online games, you are going to get a huge boost from having a 5G connection sooner or later.