Just wanted to update and add my personal experience, especially after reading and responding to this thread:
http://forums.androidcentral.com/sprint/479509-cut-your-bill-half.html
One Disclaimer: I use Google Voice for everything, so I can keep may same number, regardless of what carrier I am using.
1. I still have my grandfathered unlimited data plan with Verizon and was not giving that up, but I suspended my line without billing so I would not be charged.
2. I went to Verizon and opened a new line of service and selected the $60 1 GB Unlimited Talk/Text single line plan.
3. Called Verizon and nicely pleaded with them for their 2 GB Loyalty plan. I think it helped that I was nice, polite, knew the plan existed, and was very persistent. As always, your millage may vary.
4. I called Verizon up later and had them activate an old Blackberry on the new line of service.
5. Sprint didn't have the Nexus 6 in stock, but was glad to order it for me and it shipped the next day.
They also were happy to cut my $60 VZW Unlimited Talk/Text 2 GB plan in half.
After the phone arrived, I went back to the store, surrendered my current VZW Blackberry curve and activated the Nexus 6.
I now have a $30 Unlimited Talk/Text 2 GB data plan with Sprint. My previous VZW plan didn't include Mobile Hotspot, but my Sprint plan does.
I am a little upset that Sprint charges a $7.99 account spending limit fee to new customers, My credit is fine, but I have no credit history with Sprint. They will waive this fee if you agree to use EBilling and autopay, so I did.
They also made me pay $110 up front to cover the sales tax and an additional $75 toward the cost of the phone. I don't really care about this since it just reduces the total I owe for the phone.
I wanted the Nexus 6 specifically because I could easily take it to another carrier in the future.
However, for $30 per month, I may just keep it as a backup line when I don't need the Unlimited Data of my Verizon plan.
I have no regrets and am very happy with the outcome, the plan, and with Sprint in general. Since I did this before the 1/15/15 cuttoff, I am still eligible to apply for the $350 ETF reimbursement as well.
As others have said, the devil is in the details, but this can be a good deal depending on your situation.
I am also not trying to turn this into an ethics discussion, but it's hard for me to willingly surrender a $600 or $700 phone to Sprint when I can reactivate a different phone and surrender that one instead.
If anyone wants to comment on this aspect, feel free.