I found her interesting as a character. The benevolent GLaDoS of the game had some interesting tips, but I sometimes found the Sheikah Stone more helpful, especially in finishing a couple of sidequests.
I'd have to say (there might be a little spoilers) when you need to get the water dragons pot for the fire sanctuary, Fi actually tells you what to use. No other partner has actually helped me that much before. I would've been stuck for hours looking for something. Also Scrapper is useful too.
To me she is more robottic. Yes she helps and gives you information but she is not Midna or even the King of the Red Lions. I do consult her often but I rather fly back to the Sheikah Stone. But she gives you valuable information how to defeat a boss and I often use her for rumors etc
fi was pretty much just as annoying as midna and navi and tattl and all those terribly annoying helpers you get plus she has an autotuned voice (probably hatsune miku) yhat makes her even more annoying. she still is helpful though because because a lot of the times little hints help a lot