I have to agree with the others, though you should indeed make sure the iPhone is the correct phone as well.
To get an Android phone, she should be "Computer literate". If she asks you questions like "How do I print?", you should either get her an iPhone, or even steer here away from smart phones altogether.
However, if you ask her to open her appdata folder, and she can do this ( even if she has to look it up on the web )...Android for sure.
That being said, I have to reiterate: If she wants an iPhone just because she wants an iPhone...you're best off just going along with it for now, and later if she wants more from a phone...get her an Android then. In fact, it's very possible that just during her initial 2 weeks as she compares her iPhone to your SGS3, she may want to change to the S3. If it's early enough you should be able to take it back for a full refund and just the S3 for her. ( If you go to Best Buy they are always 30 days for returns. )