T-Mobile’s 5G network is now up and running in several US cities. This initial phase of the carrier’s 5G strategy uses the same sort of high-frequency millimeter wave network tech as Verizon, resulting in download speeds that far exceed what LTE phones can reach today. The biggest problem with millimeter wave is range: to cover a whole city, you need to have 5G nodes — the things that beam out the millimeter wave signal — all over the place. In Verizon’s case, things are still spotty. As I keep saying, 5G speeds are there on one street and gone the next. Walls and windows are also fatal for millimeter wave, so it doesn’t extend indoors.

T-Mobile says it will overcome these challenges by augmenting the millimeter wave side of its 5G network with low-band 600MHz spectrum. The latter won’t offer the same mind-blowing download rates, but low-band spectrum covers much more ground and can actually make it into buildings.

T-Mobile and Sprint are pushing for their merger so hard, partially because they believe they’ll be able to build a best-in-class 5G network by combining the best of their spectrum assets. (Sprint is currently rolling out 5G right overtop its LTE network and offers far more extensive coverage than its rivals because it’s not using millimeter wave.)

But let’s talk about how T-Mobile is doing out of the gate: pretty good. Below is a sample of the 5G speeds that I saw on T-Mobile around New York last Friday. Disregard the “LTE” icon to the left of each test, as the bulk of these were done on 5G; the Speedtest app just doesn’t yet recognize that. As you can see, the peak speeds are about half as fast as the best tests I got in Chicago when trying out Verizon’s network. But it’s still a clear jump from LTE when you’re in that 400 / 500 Mbps range. I downloaded Spider-Man: Into the Spider-Verse in about two minutes at “high” video quality from Netflix. A long Spotify playlist of over 100 songs took 15 seconds to finish up at “extreme” audio settings. In real world scenarios — even before it aids self-driving cars and makes cloud gaming more responsive — 5G will prove convenient in a pinch when you need to download something in a hurry before a flight or underground train. (Uploads, however, are still using only the 4G network for now, as is also the case with other carriers.)

It’s not winning at speed, but for now, T-Mobile can at least claim that it’s faring a little better at coverage. The carrier’s map would have you believe it’s done an impressive job of blanketing sections of New York with 5G. My real-life experience didn’t quite match that. In sections of the Financial District of Manhattan near The Verge’s office, I’d see the 5G indicator but get typical LTE download speeds. On other streets where T-Mobile’s map glowed pink to indicate 5G coverage, the phone only displayed 4G when downloading content from Netflix or Prime Video.

I saw T-Mobile’s 5G nodes on top of many smaller buildings scattered around Manhattan. And it did pay off: the Samsung Galaxy S10 5G held on to 5G on the move noticeably better than it did on Verizon’s 5G network in Chicago. I didn’t feel as though I had to freeze in place whenever I found a 5G signal to get those speedy downloads. But I’m not sure how accurate this coverage map is...

There’s one wild card here: it was an extremely hot day in New York City on Friday, with a high temperature of over 90 degrees. Samsung designed the Galaxy S10 5G to fall back to 4G LTE whenever it gets overheated. Running multiple back-to-back speed tests and downloading entire movies is a surefire way to warm up a 5G device. So I can’t be sure whether some of the situations where I only saw 4G when I was expecting 5G were due to the network or the phone itself.

Sometimes it's almost 90 degrees out and you've gotta cool a phone down to stop it from losing 5G pic.twitter.com/pEx0rsFEUj — Chris Welch (@chriswelch) June 28, 2019

Rubbing the S10 5G on my iced coffee helped keep it cool, but it was a rough environment for testing a phone. Unfortunately, Samsung limited press to just a few short hours with the device, even though it’s available in stores right now. As a result, we all walk away with an imperfect view of T-Mobile’s early 5G network — even if T-Mobile itself admits this is only stage one. It’s off to an impressive start in New York, though the patchy nature of millimeter wave is more evident when you look at T-Mobile’s other launch markets like Las Vegas and Dallas. Not great.

T-Mobile past buildout investments in NYC are paying off for the first round of 5G deployment, but elsewhere, the carrier is facing the same there-and-gone-again challenges as Verizon. Even if you’re in NYC, buying the Galaxy S10 5G on T-Mobile seems a little silly. It’ll only ever be able to take advantage of that millimeter wave part and won’t support the 600MHz 5G band when T-Mobile starts rolling that out later this year. Other phones coming in the second half of 2019 should be optimized for both, but I still think we’re at a place where your next phone upgrade won’t (and shouldn’t) be a 5G device. Your phone after that is a different story.

Photography by Chris Welch / The Verge