Where I did find 5G, I generally saw very fast download speeds in Ookla's Speedtest app. Emphasis on the word "generally" — in some places, I could consistently get north of 350Mbps down, and frequently saw speeds top out at nearly 600Mbps. Verizon claims that peak speeds can get as high as 1Gbps, but even with few people actively using the network now, none of my tests even got close. Even so, assuming you find the right location, 5G on the Moto Z3 can be really fast. (Of course, that's not to say it doesn't have competition.)
The thing to keep in mind is that there's more to using a phone than just looking at speed tests, and for now at least, the practical benefits of 5G on this smartphone haven't been game-changers. Pages loaded noticeably faster than my personal iPhone on AT&T's so-called 5GE network, but I'm not sure that's necessarily a fair comparison — as I bounced across the city, I rarely found full coverage on AT&T anyway.
5G was more helpful for playing back 1080p60 video on YouTube, though. Scrubbing through the same videos took noticeably less time on the 5G Moto Z3 than another test device I brought with me. I also downloaded PUBG Mobile (a 1.81GB file) over 5G in exactly four minutes and 30 seconds, which isn't bad considering the same download took just over eight minutes over LTE. When I launched the app to try and fumble through a round, though, I noticed that the download speeds for a 200-ish MB update file never went faster than 8MB per second, or 64Mbps. That's not nearly as fast as I was hoping for.
Months ago, Motorola nearly sold me on the idea of trying to use the 5G-enabled Moto Z3 as a superfast mobile hotspot while traveling. It's a great idea in theory, but that's all it is right now — until Motorola releases a software update at some point, the hotspot feature simply doesn't work. It's probably just as well, too, because upload speeds were comparatively tame — they generally hovered between 15 and 25Mbps. That's because only data traffic to the phone runs over the 5G network; everything you try to upload gets routed over LTE, so anyone hoping to move big files around on the go will likely be disappointed (at least for now).
As I plodded around in the rain on foot, I did find a few particularly strong pockets of 5G. The single best place I found to get a sense of the network's speed was right outside Motorola's headquarters in the city's historic Merchandise Mart. That's great if you work for Motorola, but less than ideal for, well, most residents of Chicago. I also stumbled across a decent 5G signal at the corner of Michigan and Monroe, a busy intersection just feet away from Millennium Park and the city's Art Institute.
This is where things started to get a little dicey. The typical speed tests were appropriately quick outdoors, but when I ducked into a coffee shop to try and warm up a bit, the phone quickly fell back to an LTE connection. When I pressed myself up against the coffee shop's front window, the 5G UWB logo popped up again... for just a moment. I spent the next fifteen minutes watching the phone switch between 4G and 5G connections, but the pane of glass in front of me seemed to prevent it from securely latching onto that mmWave signal.
A lackluster speed test result (roughly 45Mbps down) confirmed the issue. Those flaky connections don't just strike when indoors, either. The rest of my jaunt around the touristy spots Verizon said should have functional 5G involved lots of wandering around and freezing in place when I saw the 5G logo pop up. While that often worked, I occasionally saw the phone switching back and forth between 4G and 5G during speed tests, leading to significantly slower results.