I switched from Virgin Mobile to Google Fi. Here is my experience after 2 days of switching.
I signed up for Google Fi and ordered the Nexus 6 as soon as I received the invitation email. The phone came after 5 days of order. I opted to pay monthly for the phone. They charged just the sales tax for the phone and shipped it. Sales tax for the full price is charged even though you are paying monthly for the phone. Monthly fees for the cell phone service is not charged at this time. This starts after you activate the phone.
I chose $10 for the data. For a monthly service charge of $30 there is a tax of $3.90. Total charge per month including phone price comes to about $54. This is in MA. I am sure it will go down next month since I have not used more than 500MB per month on Virgin Mobile.
Signing up process
You need account number to transfer your number from one operator to another. You cannot get this through email. You need to call them to get it. Check the page http://www.jdhodges.com/blog/virgin-mobile-account-number-porting-numbe/ for how to get this number. Your phone number is not your account number. I got my Virgin Mobile account number the next day after I signed up. You can enter this information online on your Google Fi account. You also would loose your google voice number unless you ported that number as your new number. This was not an issue for me as I rarely used my google voice number.
Once the phone arrived I charged it and then switched it on. The phone guided through the Android initial setup process and then Fi activation. The previous operator account numbers automatically showed up since I had entered them online. The phone setup process continues while the number transfer happens. My transfer happened within minutes. This was nice as I was doing the activation on the last day of the service month at Virgin Mobile. I did not have to pay for another month just to wait for the transfer. After the process was completed internet and sms worked fine immediately.
But both incoming and outgoing calls did not work. Outgoing calls after a few rings gave the message, “the number you dialed is incorrect”. Surprisingly google Fi project has live 24/7 customer service. You can use live chat or call. I went to the online chat for help. It started instantly with no wait time. The support representative made me try several settings like turning off wi-fi, toggle airplane mode, factory reset etc. Nothing worked. After about 2 hours they finally said they will escalate to higher levels. Next day morning an email from support came with a set of steps to try out which basically involved removing sim card clearing data for apps fi and messenger and restarting the phone. After that, calls went through fine and I could received phone calls. I had not tried any calls before trying their steps. I am not sure whether their steps fixed it or the calls had just started working. Virgin mobile also disabled my account after number transfer and I was officially on Google Fi.
I had no issues with call quality so far. Everything is working seamlessly and I did not find any difference compared to my previous service.
Nexus 6 phone
I moved to Nexus 6 from Galaxy S3. I was worried about the large size initially. I think I am already used to it now. The phone is very slippery and you definitely need a case to get a better grip. I miss some things which was on S3 but not on Lollipop. Most things I commonly need are better in nexus 6. There is no separate email app for Outlook exchange. You have to use the gmail app for both gmail and exchange mails. The notifications for each mail is separate, but you need to manually switch from one account to another in the same app. Two steps instead of one. In nexus 6 you get more access from lock screen even with phone locked. You get some more details on the kind of messages you received on the lock screen. You also can use camera even if the screen is locked. But you cannot add contacts as emergency contacts accessible from lock screen. This was useful in S3 to quickly call some frequently used numbers. In nexus 6, I also like the ability to adjust volume when phone is locked. I use it a few times during the day and it is convenient to not have to enter the pin just to put the phone in vibrate mode. The battery life is also longer. It nearly comes for 2 days with light use where as S3 came only for a day.
I have not tried using the phone as GPS yet which is where most of my data use for my previous phone came from. I need to find a good car mount first. This phone does not even fit in the cup holder of the car.
The box also came with a simple phone cover for your nexus 6, a power bank and nice in ear headphones.