Wife and I just switched in late February. AT&T was $83-$89 a month for 850 shared minutes PLUS 20 cents a text...now paying $66.22 a month for 1000 minutes on EACH phone plus 1000 included text messages.
Wife and I never texted much before, but we're learning to now. Bought two refurbished slider phones with the QWERTY keyboards, and we're pretty happy with the service. I understand that in this area, Straight Talk goes thru T-Moblie...which uses AT&T towers...so we haven't lost any service or quality. Your mileage may vary.