Well, if it helps convince her any, FS is far and away the easiest
Zelda game in existence. The only really hard part is, well, getting someone else to play with you! I mean seriously, on the third quest, on the final stage, my friend and I were still fighting Octoroks. Next, Vaati flies around the room, then opens his weakpoint for you just waiting for you to wail on him. The puzzles in the game are only puzzling if your IQ is lower than 40 (esp. if you take the time to go through the practice stage in the beginning). In terms of difficulty level, FS makes WW, MC, and TP all look like the NES Zeldas in comparison.
In other words, an excellent beginner's Zelda game!
Haha, why indeed!
... Although I must admit I'd been thorougly stuck at FS with the Magnet Gloves puzzles - those are about the hardest in the game, as it ain't all that easy to manipulate it, with or without dragging your campanion along for the ride.
Those things were not properly tutored in the zero stage
Overall, it's still the easiest by far though. Even FSA had its moments of difficulty (often tied to the great amount of hostiles, I must say. But all the more rewarding in the long run).