Buying two phones, just so you can switch to the better phone, is also a pain in of itself.

Up to now GSM prepaid data offerings have been at $50/month (but with unlimited talk too).  This option at least saves $20 a month if you hardly talk much. 

Anything that gives users an option is a good thing.

Mind also that most other companies simply cut you off after reaching the 5GB mark of their so called unlimited plans.  While worse case here is 2G throttling.

Less exclusively, T-Mobile also has a $49.99 a month contract value Unlimited everything plan that can also go family for up to two lines.  Then the third is added for $15.  Though you get 2GB limit instead but unlike the exclusive deal you can use any T-Mobile phone. 

Many of these pre-paid plans tend to stick you with a crappy phone.  While this new exclusive $30 Walmart partner plan may similarly limit your phone choices you could always go for the plan I mentioned instead.

Walmart also has other T-Mobile partner deals, last I checked the selection of phones wasn’t great.  Even the data only plan charges more for just 1GB of monthly access.  So possible the $30 plan may be worse than I’m thinking but have to wait for the full details to come out to be sure.

Normal unlimited prepaid plan for T-Mobile charges $70, for $50 you only get unlimited txt and voice but data drops to 100MB, but you still get basic 2G access after going over. Cheaper plans give you even less.