Cell phone for a 12 year old?
My dd has the LG Cosmos Touch, which was free for us w/ our plan. She loves it, and it's quite easy to use. She is added to our family plan for $10/month. We find that we primarily are texting with her re:keeping in touch for pick ups, change of plans, etc. She also texts with friends rather than calling for the most part, but it hasn't been excessive.
Some folks use Tracphones, which we considered, but our current plan is fitting us well.
Yes, we also have access to a lot of parental controls, but haven't used them because it hasn't really been an issue. I would say that there has been a learning curve around what gets texted, and how quickly messages that are texted can take off. But we've had the same conversation about respecting privacy, being courteous, no matter what form the communication.