I LOVE Cingular. I've never had a problem with them, and neither has anyone else I know who has Cingular. I have friends who have other carriers (Verizon, ATT, Sprint), though, and have had nothing but trouble with all of them.
BTW, I don't understand the appeal of text-messaging. Isn't it quicker to just call the person and talk to them than to type out your message on that little tiny keypad where you have to scroll through 3 letters to get the correct letter? It seems like a huge hassle and waste of time.
You can change providers and still keep your phone number beginning on November 24th.
Article about cell phone number portability.