It sounds like a good purchase to me. Did they let you try it out before buying it? (I love my Janome, but I have the 6600P.
Once she gains confidence with the Sew-Mini she will want to graduate to your machine.
I suggest you keep your eyes open and look for a Featherweight too. That way if they are all interested, you will definitely have a machine which will last until they are teaching their grandchildren.