I can say that I have used square trade for a smartphone and I recommend against it. They insisted on repairing the device rather than replace it, and the turnaround was a full week. Also, the phone never worked properly afterwards. They fixed the problem (the earpiece was ruined when a gel material leaked into it in my pocket), but I was not impressed with their service. I ended up buying a replacement device outright.
I've also used assurion and, while I now find their pricing too high now so I no longer feel the need to do so, I had a much better experience with a few phone replacements (my son had two as well as my own issue).
Yes, I know it's anecdotal, but people should know that square trade has the right to decide to repair a device rather than replace it, and you may go many days without it while they repair it.