I was one of the first people to active a phone on Xfinity Mobile (at least that's what the representative told me when I activated). Initially I was excited to get an unlimited (kind of) plan for only $45 a month. I really like the option where I could get 2 lines with unlimited for $90 and 2 other lines for my parents at the pay by the gig, which is $12 a month. After having the service I can say that unless you will save a ton of money and want to stick with Comcast as your cable provider, you should look elsewhere.
My review:
Using the Verizon network does provide Xfinity Mobile (XM) with a huge advantage over most VMNOs. I read the articles that it will use all the same towers and be granted the same service levels but in my personal experience there seems to not be the case. My company offers 2 options for cell service, either you get a company phone on Verizon on their plan or they give you a stipend and you get your own. I choose the latter. Many of my colleges choose the former and when we travel, I get to see how the service compares. I'd estimate 90% of the time we had the same level of service but running speed tests, there were times where XM was slower. Another issue is the moving from Comcast Wifi hotspot to hotspot. Since my Comcast customer's routers are broadcasting a Wifi hotspot for their customers, when driving down a road where the houses are close to the road, you make numerous transitions. This can at times lead to issues when streaming (music or videos) where the phone seems to get confused. This occurred often enough where I turned off this feature.
Making calls worked as expected but again, there were times I had issues where my co-workers didn't.
After about 6 months my wife and I left XM and switch to T-mobile. I left my parents lines as they mostly were home and don't use the internet at all. In fact, you get a free 100mb a month which means my bill with the 2 phones will only be zero or $12 depending on the month. They really use that little of data (why I switched to XM in the first place). The service issues were small enough were I could probably have lived with it but its the other parts you give up that drove me away from XM.
First no Wifi calling... Seriously! This was a big deal as I sometimes work in large building with little cell reception. The companies know this and provide Wifi so people can stay connected. With no Wifi calling, I am left with no way to make a call.
No tablet support. I previously always had a iPad with cell service so I could save my iPhone battery for directions, save data when watching videos, and to tether my laptop too since it uses so little battery to do so. This is still not an option with XM
Having to buy their phones. This has changed and if you own or buy a Verizon or Sprint iPhone, you now can add one but those are your only options.
Mobile insurance. Initially this was not an option but you can add now. I was NOT allowed to add to the phone I had already purchased. The price is high at $12 a month. Note, T-mobile changes $12 a month but it also includes AppleCare+, which in my opinion makes it worth it.
Lastly, getting a phone unlocked. I got one phone immediately unlocked without a problem but now that I'm trying to get the second one unlocked... Let's just say it's been 10 days and the clock is still ticking.
It took 4 calls to customer service before they would even admit the phone was locked. Literally 3 people and one supervisor told me straight out that the phone was unlocked. This is even as I proved to them that it wasn't. Forth time was a charm and at least they "started the process". Now it works by you receiving an email and filling out specific questions. Once you send your responses, nothing. No auto reply, no follow ups, nothing... I called back after a few days (I was traveling so my time was limited) and the person I got said "oops, we didn't set this up correctly. She escalated to level 2 support who called me back late on Friday to tell me my option was to have the phone reactivated and then request an unlock.
To make a long story short, I received a few more call, had to do another email and still am waiting.
I strongly suggest looking elsewhere for service and if you do leave... Get your phones unlocked well beforehand.