I switched from Verizon to Walmart family plan at the beginning of the year, I had four people on my account and went down to three. Now I live out in the boondocks so my experience might not be the same as yours but the reception isn't always the greatest and there is a lot of times when there is nothing I'm talking like way out away from cities and people so if that is your physical situation its definitely something to take into consideration.
That being said most of the time like 90% everything is great, we took two iphones with us and had to buy one cheap replacement and have been happy with our service especially when the bill comes, with four people we were at almost $300.00 now its just $98.00 a month with three, every month when I get my bill I could care less about a few minutes without gps on some Georgia back road.
The cool thing with the Walmart plan is its just month to month so if I decide to change at the end of the month I just can. We weren't able to take our numbers with us (most should be able to though) but I just ported mine to Google voice and have it coming to my phone along with the new number and I've been really happy with that setup. (oh and you can check on their site to see if you can take your number with you before you buy into the plan) The other cool thing is if you see your going to go over your data you buy extra at what I feel is a really cheap rate, and it stays there in your account for whenever you need it you don't loose the extra at the end of the month. That's handy for say going on vacation and you want to use your phone to stream to a tablet. But to be honest I put $10.00 in have yet to use all of it there is so much wifi everywhere.
Hope my experience helps you make a decision.
Sandy