It's been 2+ years with Sprint/T-Mobile and the 2020 iPhone SE

 In 2020, I had completed 20 years with Sprint.  Part of that year, Sprint was part of T-Mobile.

I traded my iPhone 8 for an iPhone SE (2020), which was much the same, but more powerful.  I still have that phone today, and anticipate exchanging it for the 2022 model with 5G capabilities.

T-Mobile took away the best of Sprint's performance to add 5G capabilities.  My 100 Mbps download speed became 45 Mbps or some such.  It has been sufficient.

I recently got a OnePlus 8T and tried Mint Mobile, which is an MVNO using T-Mobile's network.  It works quite well, and at US$20/month for 10 GB, it's a decent deal, especially with 5G included.

I bought the OnePlus 8T to replace a Lenovo tablet with performance equal to my 2012/2013 Google Nexus 7 tablet.  The Snapdragon 865 is much faster than the S4 Pro I had in 2013 and therefore, much faster than that Lenovo tablet with poor 8-core MediaTek processor.  The graphics processor in the Google Nexus 7 tablet from 2013 is the same one that the 2019 Lenovo tablet was using.

In any case, 5G looks good.  I've only tested a couple of times and got one sufficient result and one good result.  If I was paying US$70 per month, I wouldn't bother, but at US$20 per month, it's a good deal.

Update 2022.05.22:

I got the 2022 iPhone SE 5G and it's good, especially for $1.25 per month.  The extra battery life and more powerful processor are somewhat noticeable, while most everything is the same.  The 5G performance is sufficiently good, as it is with the OnePlus 8T.