To help you decide how much data you need, clicking on the sourcelink will allow you to use some tools provided by the carrier to estimate how much data you will need to purchase each month. 1GB will cost you $40 plus $45 for each smartphone on the plan while 20GB runs $200 plus $30 for each smartphone or feature phone. Tablets cost $10 each to be added to a Moble Share Plan. You also receive free access to AT&T Hotspots for capable devices. For more information, check out the video below.
AT&T customers not interested in Mobile Share can continue with their current plan.
source: AT&T (1), (2) via Engadget