I use a Verizon hotspot. Much faster and much cheaper.
I think AT&T is charging $10 per gig. My shared VZW plan is much better.The wifi hotspot IMO is old technology 10 years late. I had a T-Mobile HTC phone back in 2003 where you can use it to tether your laptop and use the phone data to use the Internet. Back then it was an unknown source of data income that the phone company can't figure out how they can charge you. Now all phone comes with a data plan and if you have a family plan, you are given a FREE hotspot capability. I have data in my mercedes GLK and the Internet despite being Verizon is very slow. The iPhone data 4GLTE is faster and if it's a no charge with ATT that's ok. But if it's an extra $20 per month just to use it, I would rather use my phone as hotspot.