Normally I would never use a GPS either. And if it hadn't been for a horrible laundry accident, I would still have my old phone that couldn't do GPS.
Generally the only thing that I would really like to know is on hills what the grade is and the amount of the total climb (i.e. how fat and out of shape am I really

?).
But on the other hand, my old fairly dumb cycling computer is dying, and if I can use my phone instead (if I care that much), then I suppose I can save myself the trouble of buying a new one.
But I must admit that it would look pretty Fred to have a phone mounted on your handlebar

.