Eli Blumenthal/CNET

T-Mobile is the fourth and final major US carrier to turn on its 5G network and today, with the help of a Galaxy S10 5G phone provided by Samsung, I'll become one of the first people to try it out. I've just run the first test and guess what -- it's really fast.

Today I'm running dozens of speed tests using the Speedtest.net benchmarking app, and downloading apps, movies and TV shows. The goal is to do all of the above on the Galaxy S10 5G and a 4G Galaxy S10 Plus, which will really show the difference between 4G and 5G speeds. I'm starting my four-hour field test in Manhattan's Tompkins Square Park before traveling to other parts of the city to see how 5G fares.

Video: How fast is T-Mobile's 5G network? We took it for a test drive in New York

Here's a first impression: On the corner of 1st Ave and East 7th, T-Mobile's 5G, at 462 Mbps is more than five times faster than 4G LTE for a download. A little later, in Soho, the speed edged up to 491 Mbps and then 525 Mbps.

When I downloaded the movie Wine Country (555MB) from Netflix in Soho, it took roughly 40 seconds over 5G. On 4G LTE, there was barely any progress after 4 minutes.

To download and install the game PUBG from Google Play (a little over 2GB), it took about 2 minutes, 12 seconds over T-Mobile's 5G. On 4G LTE the game took roughly double the amount of time to download and install, coming in at 4 minutes and 25 seconds.

Downloading the first season of The Marvelous Mrs. Maisel in its highest quality (1.82GB) took just over 6 minutes, 30 seconds over 5G.

As AT&T, Verizon and Sprint raced to turn on 5G around the country, T-Mobile has been -- rather surprisingly -- sitting on the sidelines. The self-proclaimed "un-carrier," known for brash marketing and aggressive statements, didn't rush to tout a 5G broadband network to claim "first," nor did it rebrand its upgraded LTE network to a 5G-related name.

Instead, it waited, and after, testing its first 5G network in New York, it appears on early tests the wait has been worth it, though some work still needs to be done.

Running around lower Manhattan we were able to try out the millimeter wave (or mmWave) network for ourselves, seeing download speeds that rival those of home broadband, at least when on the street.

So far T-Mobile's 5G is impressive but speeds are closer to what CNET saw with Sprint 5G in Dallas than the over 1Gbps that we encountered on Verizon in Chicago or the nearly 2Gbps we got with AT&T in LA.

Eli Blumenthal/CNET

For comparison, we saw peak download speeds of roughly 1.8Gbps testing AT&T's network in Los Angeles, 1.3Gbps on Verizon in Chicago and 484Mbps on Sprint's 5G network in Dallas. Our peak download speed on T-Mobile's 5G was 583 Mbps, with speeds generally clocking in between 300 Mbps and 600 Mbps.

T-Mobile says that its available spectrum in New York is smaller compared to its other 5G cities, such as Cleveland. Speeds in those areas should be even faster than the ones I got today and potentially closer to the 5G networks offered by Verizon and AT&T.

The Big Apple is one of six cities -- alongside Atlanta, Cleveland, Dallas, Las Vegas and Los Angeles -- T-Mobile has chosen for the launch of its inaugural network. The city also seems to be the early exception for wide-scale coverage. Maps for other T-Mobile launch cities show pockets of 5G coverage, in line with early deployments of the technology by AT&T and Verizon.

While coverage was better than what we've experienced on other mmWave networks, service was limited to when we were near a 5G node and the technology still struggles to reach inside of buildings. Walking into a coffee shop on the corner of East Houston and Mott Street saw the 5G signal quickly turn to 4G LTE, even though I was only a few steps away from the street. The 5G signal quickly returned when I walked back outside.

While T-Mobile promises decent coverage of midtown and lower Manhattan and parts of downtown Brooklyn, it isn't yet blanketing the city with 5G.

T-Mobile -- like AT&T -- is hoping to combine its millimeter wave 5G with mid-band and low-band spectrum to provide a more complete coverage experience. Getting more mid-band spectrum for 5G has been one of T-Mobile's big talking points in its pitch for getting its Sprint merger approved. Sprint is currently using mid-band spectrum for its first 5G networks.

Interestingly T-Mobile told CNET that Sprint's Galaxy S10 5G should be ready to immediately take advantage of T-Mobile's 5G mmWave network should the companies' pending $26.5 billion merger gain government approval. The company's own S10 5G, however, will need to wait for the redeployment of Sprint's mid-band spectrum on the "New T-Mobile" network to be able to tap into the mid-band 5G.

Meanwhile, as great as 5G is, I've been very impressed with T-Mobile's LTE speeds. In some areas, I got close to 300 Mbps on the Galaxy S10 Plus. Downloads over 5G in these areas were still significantly faster, but the improved LTE can help provide an early taste of what 5G can do.

Coverage is just one of the growing pains T-Mobile will have to go through as it ramps up its 5G rollout with millimeter wave. On this hot June day, with temperatures approaching 90 degrees, the S10 5G would sometimes switch from 5G down to 4G to help preserve the phone and prevent it from overheating due to the high-frequency radio waves the mmWave 5G network requires and processor heavy tasks we were doing.

Eli Blumenthal, CNET

The handoff was seamless, particularly in areas with a strong LTE signal, and 5G would automatically return once the device cooled down. It is, however, something to keep an eye on as summer approaches and 5G networks come online in warmer locations.

I also had some troubles sharing the 5G connection with other devices over a WiFi hotspot. Connecting an iPhone XS Max to the Galaxy S10 5G gave me download speeds ranging from 20Mbps-60Mbps on the iPhone even though the S10 5G was still clocking download speeds of 550Mbps.

T-Mobile says it isn't placing any limitations on hotspots.

And of course, the selection of 5G-capable T-Mobile phones is currently limited to just the 6.7-inch Galaxy S10 5G, which costs $1300 and does not support T-Mobile's forthcoming low-band 5G network. Additional 5G devices are expected later this year.

All told, T-Mobile's 5G network is a lot like the early networks from its rivals. The fast speeds and comparatively decent coverage provide plenty of reasons to be excited about the future, but the still limited deployment (both with 5G outside of New York and when comparing T-Mobile's 5G coverage to its 4G LTE network), indoor issues and handling of the elements show there is still a lot of room for improvement before 5G is fully ready for primetime.

Originally published June 28 at 7:21 a.m. PT.

Updates at 8:02 a.m., 8:20 a.m., 10:24 a.m., 12:50 p.m. and 1:27 p.m. PT: Added more speed test results and thoughts.

Update, June 29.