I switched to ST a few months ago when I needed a new phone. They had a great deal on a refurbished phone. First impression was that the customer service is really terrible. I had Net10 before and it was pretty much plug and play with the sim cards. I did not have the same experience with ST. It took an hour on the phone to get my new phone service working.
I was very unhappy with the phone I purchased (Samsung Galaxy S5). Nobody could hear me talk and it had an old operating system installed that was NOT upgradeable; this strictly because of ST, had this been an unlocked phone of the same model purchased elsewhere, the software would be upgradable. This really was a huge inconvenience because this all happened a few days before my last Disney trip and I was stuck with it. Given the old operating system, I couldn't use the My Disney Experience ap. I ended up having to carry my old phone with me and access
MDE via wifi.
I sent the phone back with little hassle and got my money back. I ended up buying a Galaxy S6 from a local college kid for $80 and put a ST SIM card in it. It also was quite a pain to get it worked out with their customer service, but in the end they got it all worked out. Bringing your own phone is the way to go with Straight Talk.
As far as the service goes, I've had little problem. I had a few days where text messages were taking forever to come through or go out. I never had that happen ever in the 8 years I had Net10. I think the difference is that my Net10 phones were AT&T and my current phone is Verizon.
I would have stuck with Net10, but I couldn't buy a SIM card or any airtime cards locally. If I have any future problems with ST I will switch back. Net10 is actually about $2 less/mo for the plan I use.