We have used Stright Talk for 10 years and love it, especially the price. Their customer service was an issue but has improved over the years.
We are always careful to get a phone using Verizon towers, much better than the At&T phones on our area. May be different for you.
As someone stated you cannot use ST phones to connect other devices as you can with some.
They will sometimes notify you if you go over 2g data in a month, but we have and it keeps working and no notice of speed slow down.
We use a hotspot for data on long trips. Have been using ST but looking at a Verizon HS for future.