Thanks for the responses and welcoming me here.
It is not that I don't fully trust her, it is just that I want to be careful after hearing so many stories about women getting pregnant.
What I meant about "getting an idea about her" is this: only 1.6% of women who use birth control use this device. So there must be something unique about these women who choose such birth control. Be it convience, lifestyle, numbers of sex partners, medical reasons, etc. or that is last up to 10 years.
The more I read about these IUDs, doctors recommend that women only have one long-term sex partner. I think because it make them more susceptible to getting an uterial infection. (see that says something about the type of women that use these)
Not having to take hormones does sound like great plus for women!