Low to moderate users can benefit from the FP sims (and phones although I have no personal experience with those).
I have a SIM onthe "free plan" - 200 minutes/texts/mb per month. You can increase the Mb to 700 with FP friends.
I also have an annual 1000 promo that gives 1000 mins/texts and 1gb data per month for an annual charge of $49.99 (again FP friens can increase data to 1.5gb)
You need to go through the downgrade to free process carefully at start up to avoid default charges. Google it to make sure you get it right and your on a $0 a month plan.