Your other options are:
- Verizon Wireless, month-to-month (no difference in cost for monthly plan
just no contract and you pay full price for a device)
- Virgin Mobile (plans as low as $30/mo) is set to get the iPhone 5 soon. However, it runs on the Sprint network and no one knows whether they will allow it to have access to Sprint's LTE network.
- Cricket
- Wait for unlocked version to come out, get a prepaid SIM to T-Mobile or Straight Talk. As for your question about ST, yeah - there seems to be a vocal crowd that lost their phone number by using over 2GB data. If you don't care about your number, then go ahead - if you get cut off, you can just get another SIM for $10. If you do care about your number, go to T-Mobile...they'll just throttle you once you hit a cap.
One more thing - Cricket, Virgin Mobile, and Verizon Wireless are all official carriers. So if you get one of those, you will have visual voicemail and you don't have to tinker with any of the settings. Just a friendly FYI.